Long-term memory consolidation of new words in children with self-limited epilepsy with centro-temporal spikes

Accelerated long-term forgetting has been studied and demonstrated in adults with epilepsy. In contrast, the question of long-term consolidation (delays > 1 day) in children with epilepsy shows conflicting results. However, childhood is a period of life in which the encoding and long-term storage of new words is essential for the development of knowledge and learning. The aim of this study was therefore to investigate long-term memory consolidation skills in children with self-limited epilepsy with centro-temporal spikes (SeLECTS), using a paradigm exploring new words encoding skills and their long-term consolidation over one-week delay. As lexical knowledge, working memory skills and executive/attentional skills has been shown to contribute to long-term memory/new word learning, we added standardized measures of oral language and executive/attentional functions to explore the involvement of these cognitive skills in new word encoding and consolidation. The results showed that children with SeLECTS needed more repetitions to encode new words, struggled to encode the phonological forms of words, and when they finally reached the level of the typically developing children, they retained what they had learned, but didn't show improved recall skills after a one-week delay, unlike the control participants. Lexical knowledge, verbal working memory skills and phonological skills contributed to encoding and/or recall abilities, and interference sensitivity appeared to be associated with the number of phonological errors during the pseudoword encoding phase. These results are consistent with the functional model linking working memory, phonology and vocabulary in a fronto-temporo-parietal network. As SeLECTS involves perisylvian dysfunction, the associations between impaired sequence storage (phonological working memory), phonological representation storage and new word learning are not surprising. This dual impairment in both encoding and long-term consolidation may result in large learning gap between children with and without epilepsy. Whether these results indicate differences in the sleep-induced benefits required for long-term consolidation or differences in the benefits of retrieval practice between the epilepsy group and healthy children remains open. As lexical development is associated with academic achievement and comprehension, the impact of such deficits in learning new words is certainly detrimental.

An actor-model framework for visual sensory encoding

A fundamental challenge in neuroengineering is determining a proper artificial input to a sensory system that yields the desired perception. In neuroprosthetics, this process is known as artificial sensory encoding, and it holds a crucial role in prosthetic devices restoring sensory perception in individuals with disabilities. For example, in visual prostheses, one key aspect of artificial image encoding is to downsample images captured by a camera to a size matching the number of inputs and resolution of the prosthesis. Here, we show that downsampling an image using the inherent computation of the retinal network yields better performance compared to learning-free downsampling methods. We have validated a learning-based approach (actor-model framework) that exploits the signal transformation from photoreceptors to retinal ganglion cells measured in explanted mouse retinas. The actor-model framework generates downsampled images eliciting a neuronal response in-silico and ex-vivo with higher neuronal reliability than the one produced by a learning-free approach. During the learning process, the actor network learns to optimize contrast and the kernel's weights. This methodological approach might guide future artificial image encoding strategies for visual prostheses. Ultimately, this framework could be applicable for encoding strategies in other sensory prostheses such as cochlear or limb.

Volume holograms with linear diffraction efficiency relation by (3 + 1)D printing

We demonstrate the fabrication of volume holograms using two-photon polymerization with dynamic control of light exposure. We refer to our method as (3 + 1)D printing. Volume holograms that are recorded by interfering reference and signal beams have a diffraction efficiency relation that is inversely proportional to the square of the number of superimposed holograms. By using (3 + 1)D printing for fabrication, the refractive index of each voxel is created independently and thus, by digitally filtering the undesired interference terms, the diffraction efficiency is now inversely proportional to the number of multiplexed gratings. We experimentally demonstrated this linear dependence by recording M = 50 volume gratings. To the best of our knowledge, this is the first experimental demonstration of distributed volume holograms that overcome the 1/M2 limit.

Forward-forward training of an optical neural network

Neural networks (NNs) have demonstrated remarkable capabilities in various tasks, but their computation-intensive nature demands faster and more energy-efficient hardware implementations. Optics-based platforms, using technologies such as silicon photonics and spatial light modulators, offer promising avenues for achieving this goal. However, training multiple programmable layers together with these physical systems poses challenges, as they are difficult to fully characterize and describe with differentiable functions, hindering the use of error backpropagation algorithm. The recently introduced forward-forward algorithm (FFA) eliminates the need for perfect characterization of the physical learning system and shows promise for efficient training with large numbers of programmable parameters. The FFA does not require backpropagating an error signal to update the weights, rather the weights are updated by only sending information in one direction. The local loss function for each set of trainable weights enables low-power analog hardware implementations without resorting to metaheuristic algorithms or reinforcement learning. In this paper, we present an experiment utilizing multimode nonlinear wave propagation in an optical fiber demonstrating the feasibility of the FFA approach using an optical system. The results show that incorporating optical transforms in multilayer NN architectures trained with the FFA can lead to performance improvements, even with a relatively small number of trainable weights. The proposed method offers a new path to the challenge of training optical NNs and provides insights into leveraging physical transformations for enhancing the NN performance.

A review of materials used in tomographic volumetric additive manufacturing

Volumetric additive manufacturing is a novel fabrication method allowing rapid, freeform, layer-less 3D printing. Analogous to computer tomography (CT), the method projects dynamic light patterns into a rotating vat of photosensitive resin. These light patterns build up a three-dimensional energy dose within the photosensitive resin, solidifying the volume of the desired object within seconds. Departing from established sequential fabrication methods like stereolithography or digital light printing, volumetric additive manufacturing offers new opportunities for the materials that can be used for printing. These include viscous acrylates and elastomers, epoxies (and orthogonal epoxy-acrylate formulations with spatially controlled stiffness) formulations, tunable stiffness thiol-enes and shape memory foams, polymer derived ceramics, silica-nanocomposite based glass, and gelatin-based hydrogels for cell-laden biofabrication. Here we review these materials, highlight the challenges to adapt them to volumetric additive manufacturing, and discuss the perspectives they present.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at10.1557/s43579-023-00447-x.

NIR Light-Mediated Photocuring of Adhesive Hydrogels for Noninvasive Tissue Repair via Upconversion Optogenesis

The surgical treatments of injured soft tissues lead to further injury due to the use of sutures or the surgical routes, which need to be large enough to insert biomaterials for repair. In contrast, the use of low viscosity photopolymerizable hydrogels that can be inserted with thin needles represents a less traumatic treatment and would therefore reduce the severity of iatrogenic injury. However, the delivery of light to solidify the inserted hydrogel precursor requires a direct access to it, which is mostly invasive. To circumvent this limitation, we investigate the approach of curing the hydrogel located behind biological tissues by sending near-infrared (NIR) light through the latter, as this spectral region has the largest transmittance in biological tissues. Upconverting nanoparticles (UCNPs) are incorporated in the hydrogel precursor to convert NIR transmitted through the tissues into blue light to trigger the photopolymerization. We investigated the photopolymerization process of an adhesive hydrogel placed behind a soft tissue. Bulk polymerization was achieved with local radiation of the adhesive hydrogel through a focused light system. Thus, unlike the common methods for uniform illumination, adhesion formation was achieved with local micrometer-sized radiation of the bulky hydrogel through a gradient photopolymerization phenomenon. Nanoindentation and upright microscope analysis confirmed that the proposed approach for indirect curing of hydrogels below the tissue is a gradient photopolymerization phenomenon. Moreover, we found that the hydrogel mechanical and adhesive properties can be modulated by playing with different parameters of the system such as the NIR light power and the UCNP concentration. The proposed photopolymerization of adhesive hydrogels below the tissue opens the prospect of a minimally invasive surgical treatment of injured soft tissues.

In Vivo Retinal Pigment Epithelium Imaging using Transscleral Optical Imaging in Healthy Eyes

Objective

To image healthy retinal pigment epithelial (RPE) cells in vivo using Transscleral OPtical Imaging (TOPI) and to analyze statistics of RPE cell features as a function of age, axial length (AL), and eccentricity.

Design

Single-center, exploratory, prospective, and descriptive clinical study.

Participants

Forty-nine eyes (AL: 24.03 ± 0.93 mm; range: 21.9-26.7 mm) from 29 participants aged 21 to 70 years (37.1 ± 13.3 years; 19 men, 10 women).

Methods

Retinal images, including fundus photography and spectral-domain OCT, AL, and refractive error measurements were collected at baseline. For each eye, 6 high-resolution RPE images were acquired using TOPI at different locations, one of them being imaged 5 times to evaluate the repeatability of the method. Follow-up ophthalmic examination was repeated 1 to 3 weeks after TOPI to assess safety. Retinal pigment epithelial images were analyzed with a custom automated software to extract cell parameters. Statistical analysis of the selected high-contrast images included calculation of coefficient of variation (CoV) for each feature at each repetition and Spearman and Mann-Whitney tests to investigate the relationship between cell features and eye and subject characteristics.

Main Outcome Measures

Retinal pigment epithelial cell features: density, area, center-to-center spacing, number of neighbors, circularity, elongation, solidity, and border distance CoV.

Results

Macular RPE cell features were extracted from TOPI images at an eccentricity of 1.6° to 16.3° from the fovea. For each feature, the mean CoV was < 4%. Spearman test showed correlation within RPE cell features. In the perifovea, the region in which images were selected for all participants, longer AL significantly correlated with decreased RPE cell density (R Spearman, Rs = -0.746; P < 0.0001) and increased cell area (Rs = 0.668; P < 0.0001), without morphologic changes. Aging was also significantly correlated with decreased RPE density (Rs = -0.391; P = 0.036) and increased cell area (Rs = 0.454; P = 0.013). Lower circular, less symmetric, more elongated, and larger cells were observed in those > 50 years.

Conclusions

The TOPI technology imaged RPE cells in vivo with a repeatability of < 4% for the CoV and was used to analyze the influence of physiologic factors on RPE cell morphometry in the perifovea of healthy volunteers.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Characteristics and outcomes in patients with infective endocarditis caused by Enterococcus faecium and Enterococcus faecalis

Background

Enterococcus faecalis is the third most common cause of infective endocarditis (IE) and has been associated with a higher risk of relapse and death. Within the enterococcus species, E. faecium is the second most frequent cause of IE. As IE from E. faecalis or E. faecium most likely have different presentations and outcomes, research is needed for individualised and optimised clinical management.

Purpose

This study aims to characterise baseline characteristics and clinical outcomes for patients with IE caused by E. faecalis or E. faecium, including short- and long-term mortality and relapse. Additionally, we aim to determine risk factors associated with IE caused by the two bacterial species.

Methods

This is a retrospective study of patients hospitalised with at least one positive blood culture with E. faecalis or E. faecium between January 1, 2016 and December 31, 2018 at two large hospitals in Denmark. IE was diagnosed according to the modified Duke criteria. Index and follow-up data were collected from medical records. Categorical values were compared using chi-square test and categorial data using students t-test.

Results

614 patients had a positive blood culture with either E. faecalis (n=279) or E. faecium (n=335). Of these, 64 (10.4%) patients developed IE; E. faecalis in 56 patients (87.5%, male 83.3%, mean age 70 years (SD 14)) and E. faecium in 8 patients (12.5%, male 75.0%, mean age 65 years (SD 13)). The prevalence of IE was 20.1% for E. faecalis bacteraemia and 2.4% for E. faecium bacteraemia (p&lt;0.001). Embolic events during primary admission were seen more often in the E. faecium group (62.5%) compared to the E. faecalis group (10.7%) (p=0.002). Both groups had multiple co-morbidities without significant differences between groups (Table 1).

Nineteen (40.4%) of the patients with E. faecalis IE had a minimum of one previous admission with E. faecalis bacteraemia within the last year before the IE diagnosis, whereas this was not seen for any patients with E. faecium IE. The 30-days all-cause mortality was 5.4% for patients with E. faecalis IE and 25% for patients with E. faecium IE (p=0.22). After a median follow up of 3.1 years (IQR=0.46–3.94) all-cause mortality was 55.4% for patients with E. faecalis IE and 62.5% for patients with E. faecium IE (p=1.00) (Table 1).

Conclusion

The prevalence of IE was significantly higher in patients with E. faecalis bacteraemia than with E. faecium bacteraemia. While the prevalence of complications was higher in patients with E. faecium IE, the difference was only significant for embolic events. This indicates that E. faecium IE is associated with a worse outcome compared to the outcome in patients with E. faecalis IE. All-cause mortality was above 50% for both groups, i.e. considerably higher than generally seen in patients with IE. These findings may be of importance of management of patients with E. faecalis or with E. faecium bacteraemia – and endocarditis.

Funding Acknowledgement

Type of funding sources: None.

Long-term impact of persistent vegetations at 6 month followup after treatment of infective endocarditis: a substudy of the Partial Oral vs Intravenous Antibiotic Treatment of Endocarditis (POET) tria

Background

Our knowledge of changes in vegetation size throughout the course of infective endocarditis (IE) and the impact of persistent vegetations on mortality or embolization after completed antibiotic treatment is sparse. No study has previously investigated the prevalence or clinical impact of persistent vegetations on transthoracic echocardiography (TTE) at 6-months follow-up after ended IE treatment.

Purpose

To investigate the association between persistent vegetations at the 6-months TTE after treatment for IE and long-term prognosis as assessed in the POET trial.

Methods

The POET trial was a nationwide, multicenter RCT, randomizing 400 patients to either partial oral or intravenous (IV) antibiotic treatment of left-sided IE, after initial stabilization of infection using conventional IV therapy.

A persistent vegetation was defined as a vegetation seen on 6-months follow-up TTE (4–7 months) after ended antibiotic treatment for IE. In the POET trial, primary outcome was defined as 1) all-cause mortality, 2) unplanned cardiac surgery, 3) embolic events or 4) relapse of bacteremia, in the 5-year follow-up period. Patients without TTE due to death or lack of available TTE were excluded.

Results

Out of 400 patients, 20 were excluded due to death during 6-months follow-up, and 201 were excluded due to unavailable TTE, leaving 179 TTEs for analysis.

At 6-months follow-up, a persistent vegetation was seen in 30 patients (16.7%, 21 males (70%), mean age 69.6 years (SD 7.7)) (Table 1). Seventeen patients (56.7%) had a persistent vegetation on the aortic valve and 13 patients (43.3%) on the mitral valve. More patients without a persistent vegetation had undergone initial surgical treatment of IE than those with a vegetation (57.7 vs 23.3%, p=0.001). In all surgically treated patients with persistent vegetation at 6-months follow-up, the vegetation was found on another valve than the operated valve.

The composite primary outcome from 6-months follow-up and until 5-year follow-up occurred in 8 patients (26.7%) with a persistent vegetation, compared to 38 patients (25.5%) (p=1.00) without. (Table 2) In patients randomized for peroral treatment, no significant difference in prevalence of persistent vegetation was found (15 patients (50%) with persistent vegetations vs. 74 patients (49.7%) without, p=1.00).

Conclusion

The occurrence of persistent vegetations at 6 months follow-up was 16.7%. There was no association between persistent vegetations at 6-months follow-up and the occurrence of the primary outcome after 5 years follow-up, suggesting that the risk associated with residual vegetations after end of antibiotic treatment is negligible after 6-months.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Danish Heart Foundation

Controlling Light in Scattering Materials for Volumetric Additive Manufacturing

3D printing has revolutionized the manufacturing of volumetric components and structures in many areas. Several fully volumetric light-based techniques have been recently developed thanks to the advent of photocurable resins, promising to reach unprecedented short print time (down to a few tens of seconds) while keeping a good resolution (around 100 μm). However, these new approaches only work with homogeneous and relatively transparent resins so that the light patterns used for photo-polymerization are not scrambled along their propagation. Herein, a method that takes into account light scattering in the resin prior to computing projection patterns is proposed. Using a tomographic volumetric printer, it is experimentally demonstrated that implementation of this correction is critical when printing objects whose size exceeds the scattering mean free path. To show the broad applicability of the technique, functional objects of high print fidelity are fabricated in hard organic scattering acrylates and soft cell-laden hydrogels (at 4 million cells mL-1 ). This opens up promising perspectives in printing inside turbid materials with particular interesting applications for bioprinting cell-laden constructs.

Lock-in Raman difference spectroscopy

Shifted Excitation Raman Difference Spectroscopy (SERDS) is a non-destructive chemical analysis method capable of removing the fluorescence background and other disturbances from the Raman spectrum, thanks to the independence of the fluorescence with respect to the small difference in excitation wavelength. The spectrum difference is computed in a post-processing step. Here, we demonstrate the use of a lock-in camera to obtain an on-line analog SERDS spectra allowing longer exposure times and no saturation, leading to an improved Signal-to-Noise Ratio (SNR) and reduced data storage. Two configurations are presented: the first one uses a single laser and can remove excitation-independent disturbances, such as ambient light; the second employs two-wavelength shifted sources and removes fluorescence background similarly to SERDS. In both cases, we experimentally extrapolate the expected SNR improvement.

Volumetric Bioprinting of Organoids and Optically Tuned Hydrogels to Build Liver-Like Metabolic Biofactories

Organ- and tissue-level biological functions are intimately linked to microscale cell-cell interactions and to the overarching tissue architecture. Together, biofabrication and organoid technologies offer the unique potential to engineer multi-scale living constructs, with cellular microenvironments formed by stem cell self-assembled structures embedded in customizable bioprinted geometries. This study introduces the volumetric bioprinting of complex organoid-laden constructs, which capture key functions of the human liver. Volumetric bioprinting via optical tomography shapes organoid-laden gelatin hydrogels into complex centimeter-scale 3D structures in under 20 s. Optically tuned bioresins enable refractive index matching of specific intracellular structures, countering the disruptive impact of cell-mediated light scattering on printing resolution. This layerless, nozzle-free technique poses no harmful mechanical stresses on organoids, resulting in superior viability and morphology preservation post-printing. Bioprinted organoids undergo hepatocytic differentiation showing albumin synthesis, liver-specific enzyme activity, and remarkably acquired native-like polarization. Organoids embedded within low stiffness gelatins (<2 kPa) are bioprinted into mathematically defined lattices with varying degrees of pore network tortuosity, and cultured under perfusion. These structures act as metabolic biofactories in which liver-specific ammonia detoxification can be enhanced by the architectural profile of the constructs. This technology opens up new possibilities for regenerative medicine and personalized drug testing.

A constrained method for lensless coherent imaging of thin samples

Lensless inline holography can produce high-resolution images over a large field of view (FoV). In a previous work [Appl. Opt.60, B38 (2021)APOPAI0003-693510.1364/AO.414976], we showed that (i) the actual FoV can be extrapolated outside of the camera FoV and (ii) the effective resolution of the setup can be several times higher than the resolution of the camera. In this paper, we present a reconstruction method to recover high resolution with an extrapolated FoV image of the phase and the amplitude of a sample from aliased intensity measurements taken at a lower resolution.

Scalable optical learning operator

Today's heavy machine learning tasks are fueled by large datasets. Computing is performed with power-hungry processors whose performance is ultimately limited by the data transfer to and from memory. Optics is a powerful means of communicating and processing information, and there is currently intense interest in optical information processing for realizing high-speed computations. Here we present and experimentally demonstrate an optical computing framework called scalable optical learning operator, which is based on spatiotemporal effects in multimode fibers for a range of learning tasks including classifying COVID-19 X-ray lung images, speech recognition and predicting age from images of faces. The presented framework addresses the energy scaling problem of existing systems without compromising speed. We leverage simultaneous, linear and nonlinear interaction of spatial modes as a computation engine. We numerically and experimentally show the ability of the method to execute several different tasks with accuracy comparable with a digital implementation.

Degradation study on molecules released from laser-based jet injector

Development of needle-free methods to administer injectable therapeutics has been researched for a few decades. We focused our attention on a laser-based jet injection technique where the liquid-jet actuation mechanism is based on optical cavitation. This study investigates the potential damage to therapeutic molecules which are exposed to nanosecond laser pulses in the configuration of a compact laser-based jet injection device. Implementation of a pulsed laser source at 1574 nm wavelength allowed us to generate jets from pure water solutions and circumvent the need to reformulate therapeutics with absorbing dyes. We performed H1-NMR analysis on exposed samples of Lidocaine and δ-Aminolevulinic acid. We made several tests with linear and plasmid DNA to assess the structural integrity and functional potency after ejection with our device. The tests showed no significant degradation or detectable side products, which is promising for further development and eventually clinical applications.

An Intrinsically-Adhesive Family of Injectable and Photo-Curable Hydrogels with Functional Physicochemical Performance for Regenerative Medicine

Attaching hydrogels to soft internal tissues is crucial for the development of various biomedical devices. Tough sticky hydrogel patches present high adhesion, yet with lack of injectability and the need for treatment of contacting surface. On the contrary, injectable and photo-curable hydrogels are highly attractive owing to their ease of use, flexibility of filling any shape, and their minimally invasive character, compared to their conventional preformed counterparts. Despite recent advances in material developments, a hydrogel that exhibits both proper injectability and sufficient intrinsic adhesion is yet to be demonstrated. Herein, a paradigm shift is proposed toward the design of intrinsically adhesive networks for injectable and photo-curable hydrogels. The bioinspired design strategy not only provides strong adhesive contact, but also results in a wide window of physicochemical properties. The adhesive networks are based on a family of polymeric backbones where chains are modified to be intrinsically adhesive to host tissue and simultaneously form a hydrogel network via a hybrid cross-linking mechanism. With this strategy, adhesion is achieved through a controlled synergy between the interfacial chemistry and bulk mechanical properties. The functionalities of the bioadhesives are demonstrated for various applications, such as tissue adhesives, surgical sealants, or injectable scaffolds.

Pulsatile Flow-Induced Fatigue-Resistant Photopolymerizable Hydrogels for the Treatment of Intracranial Aneurysms

An alternative intracranial aneurysm embolic agent is emerging in the form of hydrogels due to their ability to be injected in liquid phase and solidify in situ. Hydrogels have the ability to fill an aneurysm sac more completely compared to solid implants such as those used in coil embolization. Recently, the feasibility to implement photopolymerizable poly(ethylene glycol) dimethacrylate (PEGDMA) hydrogels in vitro has been demonstrated for aneurysm application. Nonetheless, the physical and mechanical properties of such hydrogels require further characterization to evaluate their long-term integrity and stability to avoid implant compaction and aneurysm recurrence over time. To that end, molecular weight and polymer content of the hydrogels were tuned to match the elastic modulus and compliance of aneurysmal tissue while minimizing the swelling volume and pressure. The hydrogel precursor was injected and photopolymerized in an in vitro aneurysm model, designed by casting polydimethylsiloxane (PDMS) around 3D printed water-soluble sacrificial molds. The hydrogels were then exposed to a fatigue test under physiological pulsatile flow, inducing a combination of circumferential and shear stresses. The hydrogels withstood 5.5 million cycles and no significant weight loss of the implant was observed nor did the polymerized hydrogel protrude or migrate into the parent artery. Slight surface erosion defects of 2–10 μm in depth were observed after loading compared to 2 μm maximum for non-loaded hydrogels. These results show that our fine-tuned photopolymerized hydrogel is expected to withstand the physiological conditions of an in vivo implant study.

Hemoglobin level at stabilization is associated with long-term all-cause mortality in patients with left-sided endocarditis, a POET substudy

Background

Left-sided infectious endocarditis (IE) has a high 1-year mortality. Anemia is a common finding in patients with IE, yet little is known about frequency, severity, and associated outcomes in this setting.

Purpose

To examine the relationship between Hemoglobin (Hgb) level measured at IE stabilization (time of randomization) in the Partial Oral versus intravenous Antibiotic Treatment of Endocarditis (POET) trial - and long-term all-cause mortality.

Methods

In the POET trial, 400 patients with left-sided IE were randomized, after medical and/or surgical stabilization, to conventional antibiotic treatment or partial oral treatment. Only non-surgically treated patients were considered in this study. Patients were divided by quartiles into four groups based on Hgb level at randomization.

Results

We examined 248 patients with non-surgically treated IE. Median time from diagnosis of IE to randomization was 14 days (IQ 12–19). At long-term follow-up (median 3.2 years, IQ 2.18–4.60), 71 patients had died (28.6%). Patients in the lowest quantile (Hgb ≤6.0 mmol) had a HR of 4.17 (95% CI 1.81–9.61, p&lt;0.001) for death compared to patients in the highest quantile (Hgb &gt;7.5 mmol/L). This association remained significant after multivariable adjustment for age, sex, renal disease, C-Reactive Protein, and Prosthetic heart valve (HR 2.69, 95% CI 1.11–6.50); p=0.028).

Conclusion

Low Hemoglobin level at stabilization in patients with IE was associated with an increased risk of long-term mortality. Whether intensified treatment of anemia in patients with IE could improve long-term outcome requires investigation.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The Danish Heart Foundation, The Capital Regions Research Council

Phase sensitivity in differential phase contrast microscopy: limits and strategies to improve it

The phase sensitivity limit of Differential Phase Contrast (DPC) with partially coherent light is analyzed in details. The parameters to tune phase sensitivity, such as the diameter of illumination, the numerical aperture of the objective, and the noise of the camera are taken into account to determine the minimum phase contrast that can be detected. We found that a priori information about the sample can be used to fine-tune these parameters to increase phase contrast. Based on this information, we propose a simple algorithm to predict phase sensitivity of a DPC setup, which can be performed before the setup is built. Experiments confirm the theoretical findings.

Needle-free delivery of fluids from compact laser-based jet injector

Jet injection devices have been studied and developed for transdermal drug delivery to avoid the use of needles. Due to bulky actuation mechanisms, they are limited to body areas that are easy to reach such as skin. Here, we demonstrate a thin and long liquid delivery system (e.g. flexible and 30 cm long with 1.2 mm outer diameter) compatible with minimally invasive surgical procedures. The actuation mechanism is based on optical cavitation in a capillary nozzle where a laser pulse is delivered via a multimode optical fibre. We show good controllability of the jet speed by varying the actuation laser fluence. The generated jets can successfully penetrate into a 1% agarose gel which is representative of the mechanical properties of several soft body tissues. We further observe that when the system is used in a low laser energy regime (<60 μJ), the ejection is in the form of the single droplet which is promising for fluid delivery with high volume precision or drop-on-demand inkjet printing. The jet injection system we propose has the potential to deliver heat-sensitive therapeutics as we show processing of biomolecules without altering their functionality.

All-fiber spatiotemporally mode-locked laser with multimode fiber-based filtering

We demonstrate the first all-fiber multimode spatiotemporally mode-locked laser. The oscillator generates dissipative soliton pulses at 1036 nm with 12 mW average power, 6.24 ps duration, and 24.3 MHz repetition rate. The reported pulse energy (0.5 nJ) represents ∼4 times improvement over the previously reported single-mode all-normal dispersion mode-locked lasers with multimode interference-based filtering. Numerical simulations are performed to investigate the cavity and spatiotemporal mode-locking dynamics. The all-fiber oscillator we present shows promise for practical use since it can be fabricated simply.

Transscleral Optical Phase Imaging of the Human Retina

In-vivo observation of the human retina at the cellular level is crucial to detect the first signs of retinal diseases and properly treat them. Despite the phenomenal advances in adaptive optics (AO) systems, clinical imaging of many retinal cells is still elusive due to the low signal-to-noise ratio induced by transpupillary illumination. We present a transscleral optical phase imaging (TOPI) method, which relies on high-angle oblique illumination of the retina, combined with AO, to enhance cell contrast. Examination of eleven healthy volunteer eyes, without pupil dilation, shows the ability of this method to produce in-vivo images of retinal cells, from the retinal pigment epithelium to the nerve fibre layer. This method also allows the generation of high-resolution label-free ex-vivo phase images of flat-mounted retinas. The 4.4°x 4.4° field-of-view in-vivo images are recorded in less than 10 seconds, opening new avenues in the exploration of healthy and diseased retinas.

Fully automated detection, segmentation, and analysis of in vivo RPE single cells

OBJECTIVE

To develop a fully automated method of retinal pigmented epithelium (RPE) cells detection, segmentation and analysis based on in vivo cellular resolution images obtained with the transscleral optical phase imaging method (TOPI).

METHODS

Fourteen TOPI-RPE images from 11 healthy individuals were analysed. The developed image processing method encompassed image filtering and normalisation, detection and removal of blood vessels, cell detection and cell membrane segmentation. The produced measures were cellular density of RPE layer, cell area, number of neighbouring cells, eccentricity, circularity and solidity. In addition, we proposed coefficient of variation (CV) of RPE cellular membrane (CMD_CV) and the solidity of the RPE cell membrane-shape as new metrics for the assessment of RPE single cells.

RESULTS

The observed median cellular density of the RPE layer was 3743 cells/µm² (interquartile rate (IQR) 1687), with a median observed RPE cell area of 193 µm² (IQR 141). The mean number of neighbouring cells was 5.22 (standard deviation (SD) 0.05) per RPE cell. The mean RPE cell eccentricity was 0.67 (SD 0.02), median circularity 0.83 (IQR 0.01), and median solidity 0.92 (IQR 0.00). The median CMD_CV was 0.19 (IQR 0.02). The method is characterised by a median image processing and analysis time of 48 sec (IQR 12) per image.

CONCLUSIONS

The present study provides the first fully automated quantitative assessment of human RPE single cells in vivo. The method provides a baseline for future research in the field of clinical ophthalmology, enabling characterisation and diagnostics of retinal diseases at the single-cell level.

In vitro Implementation of Photopolymerizable Hydrogels as a Potential Treatment of Intracranial Aneurysms

Intracranial aneurysms are increasingly being treated with endovascular therapy, namely coil embolization. Despite being minimally invasive, partial occlusion and recurrence are more frequent compared to open surgical clipping. Therefore, an alternative treatment is needed, ideally combining minimal invasiveness and long-term efficiency. Herein, we propose such an alternative treatment based on an injectable, radiopaque and photopolymerizable polyethylene glycol dimethacrylate hydrogel. The rheological measurements demonstrated a viscosity of 4.86 ± 1.70 mPa.s, which was significantly lower than contrast agent currently used in endovascular treatment (p = 0.42), allowing the hydrogel to be injected through 430 μm inner diameter microcatheters. Photorheology revealed fast hydrogel solidification in 8 min due to the use of a new visible photoinitiator. The addition of an iodinated contrast agent in the precursor contributed to the visibility of the precursor injection under fluoroscopy. Using a customized light-conducting microcatheter and illumination module, the hydrogel was implanted in an in vitro silicone aneurysm model. Specifically, in situ fast and controllable injection and photopolymerization of the developed hydrogel is shown to be feasible in this work. Finally, the precursor and the polymerized hydrogel exhibit no toxicity for the endothelial cells. Photopolymerizable hydrogels are expected to be promising candidates for future intracranial aneurysm treatments.

Repetitive regime of highly focused liquid microjets for needle-free injection

Fast liquid jets are investigated for use as a needle-free drug delivery system into an elastic tissue such as skin. Using smaller jet diameters in a repetitive regime can mitigate bruising and pain associated with current injectors. In this study, we aim to unravel the potential of the method to deliver liquids into biological tissues having higher elasticity than healthy skin (i.e >60 kPa). To address this challenge, we have implemented a laser-based jetting system capable of generating supersonic liquid microjets in a repetitive regime. We provide insights on the penetration of microjets into hydrogel samples with elastic modulus ranging from 16 kPa to 0.5 MPa. The unprecedented speeds of injection (>680 m/s) together with a newly introduced repetitive regime opens possibilities for usage in needle-free drug administration into materials with elasticity covering the wide spectrum of biological soft tissues like blood vessels, all skin layers, scarred or dried skin or tumors.

High-resolution tomographic volumetric additive manufacturing

In tomographic volumetric additive manufacturing, an entire three-dimensional object is simultaneously solidified by irradiating a liquid photopolymer volume from multiple angles with dynamic light patterns. Though tomographic additive manufacturing has the potential to produce complex parts with a higher throughput and a wider range of printable materials than layer-by-layer additive manufacturing, its resolution currently remains limited to 300 µm. Here, we show that a low-étendue illumination system enables the production of high-resolution features. We further demonstrate an integrated feedback system to accurately control the photopolymerization kinetics over the entire build volume and improve the geometric fidelity of the object solidification. Hard and soft centimeter-scale parts are produced in less than 30 seconds with 80 µm positive and 500 µm negative features, thus demonstrating that tomographic additive manufacturing is potentially suitable for the ultrafast fabrication of advanced and functional constructs.

Tomographic additive manufacturing produces complex parts with a wide range of printable materials but remains limited in terms of resolution. Here, the authors tune the étendue of the light source and accurately control the photopolymerization kinetics using an integrated feedback system, leading to the fabrication of high resolution features.

Improving antibiotic treatment of bacterial biofilm by hyperbaric oxygen therapy: Not just hot air

Bacteria and fungi show substantial increased recalcitrance when growing as infectious biofilms. Chronic infections caused by biofilm growing microorganisms is considered a major problem of modern medicine. New strategies are needed to improve antibiotic treatment of biofilms. We have improved antibiotic treatment of bacterial biofilms by reviving the dormant bacteria and thereby make them susceptible to antibiotics by means of reoxygenation. Here we review the rationale for associating lack of oxygen with low susceptibility in infectious biofilm, and how hyperbaric oxygen therapy may result in reoxygenation leading to enhanced bactericidal activity of antibiotics. We address issues of feasibility and potential adverse effects regarding patient safety and development of resistance. Finally, we propose means for supplying reoxygenation to antibiotic treatment of infectious biofilm with the potential to benefit large groups of patients.

P3665Prevalence of infective endocarditis in patients with positive blood cultures: a Danish nationwide study

Background

Increasing attention has been given to the risk of infective endocarditis (IE) in patients with certain blood stream infections (BSI). Previous studies have been conducted on selected patient cohorts, yet unselected data are sparse.

Purpose

To investigate the nationwide prevalence of diagnosed IE in BSIs with bacteria typically associated with IE.

Methods

By crosslinking nationwide registries from 2010–2016, we identified patients with BSIs typically associated with IE: Enterococcus faecalis, Staphylococcus, Streptococcus spp., and coagulase negative staphylococci (CoNS) and examined the concurrent IE prevalence. A trend test was used to examine temporal changes in the prevalence of IE.

Results

In total 60,119 BSIs, distributed with 15,407, 16,790, and 27,922 BSIs were identified in the periods of 2010–2011, 2012–2013, and 2014–2016, respectively.

Patients with E. Faecalis had the highest prevalence of diagnosed IE (16.3%) followed by S. aureus (10.2%), Streptococcus spp. (7.3%), and CoNS (1.6%) (Figure). During the study period, the prevalence of IE among patients with E. faecalis increased significantly (p=0.003), Male patients had higher prevalence of IE for all microorganisms investigated compared with females. A significant increase in the prevalence of IE was seen for E. faecalis, Streptococcus spp., and CoNS with increasing age.

Percent with endocarditis

Conclusion

For E. faecalis BSI, 1 in 6 had IE, for S. aureus BSI 1 in 10 had IE, and for Streptococcus spp. 1 in 14 had IE. Our results support screening for IE in patients with E. faecalis, S. aureus, or Streptococcus spp. BSI in order to offer appropriate therapy.

Volumetric Bioprinting of Complex Living-Tissue Constructs within Seconds

Biofabrication technologies, including stereolithography and extrusion-based printing, are revolutionizing the creation of complex engineered tissues. The current paradigm in bioprinting relies on the additive layer-by-layer deposition and assembly of repetitive building blocks, typically cell-laden hydrogel fibers or voxels, single cells, or cellular aggregates. The scalability of these additive manufacturing technologies is limited by their printing velocity, as lengthy biofabrication processes impair cell functionality. Overcoming such limitations, the volumetric bioprinting of clinically relevant sized, anatomically shaped constructs, in a time frame ranging from seconds to tens of seconds is described. An optical-tomography-inspired printing approach, based on visible light projection, is developed to generate cell-laden tissue constructs with high viability (>85%) from gelatin-based photoresponsive hydrogels. Free-form architectures, difficult to reproduce with conventional printing, are obtained, including anatomically correct trabecular bone models with embedded angiogenic sprouts and meniscal grafts. The latter undergoes maturation in vitro as the bioprinted chondroprogenitor cells synthesize neo-fibrocartilage matrix. Moreover, free-floating structures are generated, as demonstrated by printing functional hydrogel-based ball-and-cage fluidic valves. Volumetric bioprinting permits the creation of geometrically complex, centimeter-scale constructs at an unprecedented printing velocity, opening new avenues for upscaling the production of hydrogel-based constructs and for their application in tissue engineering, regenerative medicine, and soft robotics.

Selective femtosecond laser ablation via two-photon fluorescence imaging through a multimode fiber

We demonstrate the ability of a multimode fiber probe to provide two-photon fluorescence (TPF) imaging feedback that guides the femtosecond laser ablation (FLA) in biological samples for highly selective modifications. We implement the system through the propagation of high power femtosecond pulses through a graded-index (GRIN) multimode fiber and we investigate the limitations posed by the high laser peak intensities required for laser ablation. We demonstrate that the GRIN fiber probe can deliver laser intensities up to 1.5x10¹³ W/cm², sufficient for the ablation of a wide range of materials, including biological samples. Wavefront shaping through an ultrathin probe of around 400 μm in diameter is used for diffraction limited focusing and digital scanning of the focus spot. Selective FLA of cochlear hair cells is performed based on the TPF images obtained through the same multimode fiber probe.

Raman imaging through multimode sapphire fiber

We report on a sapphire fiber Raman imaging probe's use for challenging applications where access is severely restricted. Small-dimension Raman probes have been developed previously for various clinical applications because they show great capability for diagnosing disease states in bodily fluids, cells, and tissues. However, applications of these sub-millimeter diameter Raman probes were constrained by two factors: first, it is difficult to incorporate filters and focusing optics at such small scale; second, the weak Raman signal is often obscured by strong background noise from the fiber probe material, especially the most commonly used silica, which has a strong broad background noise in low wavenumbers (<500-1700 cm^-1). Here, we demonstrate the thinnest-known imaging Raman probe with a 60 μm diameter Sapphire multimode fiber in which both excitation and signal collection pass through. This probe takes advantage of the low fluorescence and narrow Raman peaks of Sapphire, its inherent high temperature and corrosion resistance, and large numerical aperture (NA). Raman images of Polystyrene beads, carbon nanotubes, and CaSO₄ agglomerations are obtained with a spatial resolution of 1 μm and a field of view of 30 μm. Our imaging results show that single polystyrene bead (~15 µm diameter) can be differentiated from a mixture with CaSO₄ agglomerations, which has a close Raman shift.

A comparative performance analysis of stand-alone, off-grid solar-powered sodium hypochlorite generators

Sodium hypochlorite (NaClO) is a chemical commodity widely employed as a disinfection agent in water treatment applications. Its production commonly follows electrochemical routes in an undivided reactor. Powering the process with photovoltaic (PV) electricity holds the potential to install stand-alone, independent generators and reduce the NaClO production cost. This study reports the comparative assessment of autonomous, solar-powered sodium hypochlorite generators employing different photovoltaic (PV) technologies: silicon hetero-junction (SHJ) and multi-junction (MJ) solar cells. For Si hetero-junctions, the series connection of either four or five SHJ (4SHJ and 5SHJ, respectively) cells was implemented to obtain the reaction potential required. MJ cells were illuminated by a novel planar solar concentrator that guarantees solar tracking with minimal linear displacements. The three solar-hypochlorite generators were tested under real atmospheric conditions, demonstrating solar-to-chemical conversion efficiencies (SCE) of 9.8% for 4SHJ, 14.2% for 5SHJ and 25.1% for MJ solar cells, respectively. Simulations based on weather databases allowed us to assess efficiencies throughout the entire model year and resulted in specific sodium hypochlorite yearly production rates between 7.2–28 g_NaClO cm⁻² (referred to the PV surface), depending on the considered PV technology, location, and deployment of electronics converters. The economic viability and competitiveness of solar hypochlorite generators have been investigated and compared with an analog disinfection system deploying ultraviolet lamps. Our study demonstrates the feasibility of off-grid, solar-hypochlorite generators, and points towards the implementation of SHJ solar cells as a reliable technology for stand-alone solar-chemical devices.

Solar-powered electrochemical technologies can be employed to generate valuable chemical commodities on-site. We demonstrate solar-driven production of sodium hypochlorite, a widely employed water disinfection agent.

Composite Double-Network Hydrogels To Improve Adhesion on Biological Surfaces

Despite the development of hydrogels with high mechanical properties, insufficient adhesion between these materials and biological surfaces significantly limits their use in the biomedical field. By controlling toughening processes, we designed a composite double-network hydrogel with ∼90% water content, which creates a dissipative interface and robustly adheres to soft tissues such as cartilage and meniscus. A double-network matrix composed of covalently cross-linked poly(ethylene glycol) dimethacrylate and ionically cross-linked alginate was reinforced with nanofibrillated cellulose. No tissue surface modification was needed to obtain high adhesion properties of the developed hydrogel. Instead, mechanistic principles were used to control interfacial crack propagation. Comparing to commercial tissue adhesives, the integration of the dissipative polymeric network on the soft tissue surfaces allowed a significant increase in the adhesion strength, such as ∼130 kPa for articular cartilage. Our findings highlight the significant role of controlling hydrogel structure and dissipation processes for toughening the interface. This research provides a promising path to the development of highly adhesive hydrogels for tissues repair.

Multimode optical fiber transmission with a deep learning network

Multimode fibers (MMFs) are an example of a highly scattering medium, which scramble the coherent light propagating within them to produce seemingly random patterns. Thus, for applications such as imaging and image projection through an MMF, careful measurements of the relationship between the inputs and outputs of the fiber are required. We show, as a proof of concept, that a deep neural network can learn the input-output relationship in a 0.75 m long MMF. Specifically, we demonstrate that a deep convolutional neural network (CNN) can learn the nonlinear relationships between the amplitude of the speckle pattern (phase information lost) obtained at the output of the fiber and the phase or the amplitude at the input of the fiber. Effectively, the network performs a nonlinear inversion task. We obtained image fidelities (correlations) as high as ~98% for reconstruction and ~94% for image projection in the MMF compared with the image recovered using the full knowledge of the system transmission characterized with the complex measured matrix. We further show that the network can be trained for transfer learning, i.e., it can transmit images through the MMF, which belongs to another class not used for training/testing.

Le syndrome postgarde de nuit chez les médecins urgentistes : caractéristiques et facteurs influençants

Introduction : Les urgentistes connaissent une privation de sommeil en lendemain de garde. Beaucoup ont des perceptions ou des comportements inhabituels que nous appelons syndrome post-garde de nuit (PGN). L’objectif principal était de caractériser le syndrome PGN des urgentistes. Les objectifs secondaires étaient d’établir une note évaluant le syndrome PGN et de déterminer les facteurs influençant ce syndrome PGN.

Méthode : Étude prospective de cohorte, observationnelle, multicentrique, auprès des urgentistes du Gard et de l’Hérault entre janvier et juin 2017. Deux questionnaires informatiques anonymes étaient diffusés aux structures d’urgences du Gard et de l’Hérault. En journée normale, hors sortie de garde, un questionnaire colligeait les symptômes ressentis habituellement en lendemain de garde, à coter entre 0 et 10. En sortie de garde, un autre questionnaire s’intéressait au ressenti de la garde réalisée et aux caractéristiques de cette garde. Les médecins étaient encouragés à répondre aux deux questionnaires.

Résultats : Cent treize médecins (45 %) ont répondu, 67 (59 %) à distance d’une garde et 46 (41 %) en post-garde immédiat. Le syndrome PGN comprend des symptômes somatiques (échelle visuelle analogique (EVA) = 5 [2–8]), comportementaux (EVA = 7 [3–8]), liés à l’humeur (EVA = 7[5–8]) et psychiques (EVA = 6 [4–8]). Ces symptômes en post-garde immédiat étaient ressentis de manière moins importante que lorsque décrit à distance (respectivement p = 0,001, p <0,001, p < 0,001, p = 0,002). Les gardes de SMUR (service mobile d’urgence et de réanimation) et de traumatologie étaient associées à un syndrome PGN moins marqué (respectivement p =0,035 et p = 0,02) que les gardes des filières médico-chirurgicales.

Conclusion : Il s’agit de la première évaluation du syndrome PGN chez les urgentistes français. Les symptômes en sont moins importants en post-garde immédiat. Les gardes de traumatologie et de SMUR semblent mieux tolérées.

Compact lensless subpixel resolution large field of view microscope

We report on a method to increase the spatial resolution in a compact lensless microscope. A compact side illumination is fabricated to illuminate the sample with a collimated beam by diffraction from a volume phase grating. The wavelength of a semi-conductor laser source (vertical-cavity surface-emitting laser) is tuned with the injection current to alter the illumination direction by wavelength selective diffraction from the volume phase grating. The angle tuning is such that several subpixel shifted digital inline holograms are obtained. The stack of holograms is then processed in a pixel super-resolution reconstruction algorithm. The amplitude of the sample is reconstructed with subpixel resolution over a large field of view (FOV). The technique is demonstrated on a 1951 USAF test target. A resolution of ∼2.76  μm, over a FOV of ∼28  mm², is demonstrated for a device of <2  cm height. The original pixel size was 5.2 μm demonstrating the subpixel resolution.

Effect of backscattering in phase contrast imaging of the retina

The observation of retinal cellular structures is fundamental to the understanding of eye pathologies. However, except for rods and cones, most of the retinal microstructures are weakly reflective and thus difficult to image with state of the art reflective optical imaging techniques such as optical coherence tomography. Recently, we demonstrated the possibility of obtaining the phase contrast of retinal cells in the eye using oblique illumination of the retina. Indeed, by illuminating the eye with incoherent oblique illumination, we obtain a secondary oblique illumination from the backscattered light which can then be used to obtain phase contrast in an effective transmission-like configuration. In this technique, a weak phase signal is modulated over an intense background. Maximizing this phase contrast is thus crucial for the image quality. Here, we investigate the parameters that affect phase contrast by modelling image formation with the backscattered light. We find that the key parameter for maximizing contrast is the intensity profile of the backscattered light. Specifically, the gradient of the profile is found to be proportional to the phase contrast. We validate the model by comparing simulations with experimental results on ex-vivo retina samples.

Compact in-line lensfree digital holographic microscope

Phase imaging provides intensity contrast to visualize transparent samples such as found in biology without any staining. Among them, digital holographic microscopy (DHM) is a well-known quantitative phase method. Lensfree implementations of DHMs offer the added advantage to provide large field of views (several mm2 compared to several hundred μm2) and more compact setups that traditional DHM which have high quality microscope objectives. In this article, a lensfree DHM is presented using a side illumination technique in order to further reduce the device size. Its practical use is described and results on a transparent (phase only) sample are shown.

Single-photon three-dimensional microfabrication through a multimode optical fiber

Two-photon polymerization (TPP) processes have enabled the fabrication of advanced and functional microstructures. However, most TPP platforms are bulky and require the use of expensive femtosecond lasers. Here, we propose an inexpensive and compact alternative to TPP by adapting an endoscopic imaging system for single-photon three-dimensional microfabrication. The wavefront of a visible continuous-wave laser beam is shaped so that it focuses into a photoresist through a 5 cm long ultra-thin multimode optical fiber (∅70 μm, NA 0.64). Using this device, we show that single-photon polymerization can be confined to the phase-controlled focal spot thanks to the non-linearity of the photoresist, likely due to oxygen radical scavenging. Thus, by exploiting this non-linearity with a specific overcuring method we demonstrate single-photon three-dimensional fabrication of solid and hollow microstructures through a multimode fiber with a 1.0-μm lateral and 21.5-μm axial printing resolution. This opens up new possibilities for advanced and functional microfabrication through endoscopic probes with inexpensive laser sources.

A 25.1% Efficient Stand-Alone Solar Chloralkali Generator Employing a Microtracking Solar Concentrator

Chlorine is a large-scale chemical commodity produced via the chloralkali process, which involves the electrolysis of brine in a membrane-based electrochemical reactor. The reaction is normally driven by grid electricity; nevertheless, the required combination of voltage-current can be guaranteed using renewable power (i.e., photovoltaic electricity). This study demonstrates an off-grid solar-powered chlorine generator that couples a novel planar solar concentrator, multijunction InGaP/GaAs/InGaAsNSb solar cells and an electrochemical cell fabricated via additive manufacturing. The planar solar concentrator consists of an array of seven custom injection-molded lenses and uses microtracking to maintain a ± 40° wide angular acceptance. Triple-junction solar cells provide the necessary potential (open-circuit voltage, V OC = 3.16 V) to drive the electrochemical reactions taking place at a De Nora DSA insoluble anode and a nickel cathode. This chloralkali generator is tested under real atmospheric conditions and operated at a record 25.1% solar-to-chemical conversion efficiency (SCE). The device represents the proof-of-principle of a new generation stand-alone chlorine production system for off-grid utilization in remote and inaccessible locations.

Compact lensless off-axis transmission digital holographic microscope

Current compact lensless holographic microscopes are based on either multiple angle in-line holograms, multiple wavelength illumination or a combination thereof. Complex computational algorithms are necessary to retrieve the phase image which slows down the visualization of the image. Here we propose a simple compact lensless transmission holographic microscope with an off-axis configuration which simplifies considerably the computational processing to visualize the phase images and opens the possibility of real time phase imaging using off the shelf smart phone processors and less than $3 worth of optics and detectors, suitable for broad educational dissemination. This is achieved using a side illumination and analog hologram gratings to shape the reference and signal illumination beams from one light source. We demonstrate experimentally imaging of cells with a field of view (FOV) of ~12mm², and a resolution of ~3.9μm.