An implantable device for wireless monitoring of diverse physio-behavioral characteristics in freely behaving small animals and interacting groups

Implantable bioelectronics and wearable sensors for kidney health and disease

Established clinical practices for monitoring kidney health and disease - including biopsy and serum biomarker analysis - suffer from practical limitations in monitoring frequency and lack adequate sensitivity for early disease detection. Engineering advances in biosensors have led to the development of wearable and implantable systems for monitoring of kidney health. Non-invasive microfluidic systems have demonstrated utility in the detection of kidney-relevant biomarkers, such as creatinine, urea and electrolytes in peripheral body fluids such as sweat, interstitial fluid, tears and saliva. Implantable systems may aid the identification of early transplant rejection through analysis of organ temperature and perfusion, and enable real-time assessment of inflammation through the use of thermal sensors. These technologies enable continuous, real-time monitoring of kidney health, offering complementary information to standard clinical procedures to alert physicians of changes in kidney health for early intervention. In this Review, we explore devices for monitoring renal biomarkers in peripheral biofluids and discuss developments in implantable sensors for the direct measurement of the local, biophysical properties of kidney tissue. We also describe potential clinical applications, including monitoring of chronic kidney disease, acute kidney injury and allograft health.

Physio-fUS: a tissue-motion based method for heart and breathing rate assessment in neurofunctional ultrasound imaging

BACKGROUND

Recent studies have shown growing evidence that brain function is closely synchronised with global physiological parameters. Heart rate is linked to various cognitive processes and a strong correlation between neuronal activity and breathing has been demonstrated. These findings highlight the significance of monitoring these key physiological parameters during neuroimaging as they provide valuable insights into the overall brain function. Today, in neuroimaging, assessing these parameters requires additional cumbersome devices or implanted electrodes. Here we demonstrate that ultrasonic neurofunctional imaging data alone is sufficient to extract these parameters.

METHODS

In this work, we performed ultrafast ultrasound imaging in male rodents and human neonates, and we extracted heart and breathing rates from local tissue motion assessed by raw ultrasound data processing. Such "Physio-fUS" automatically selects two specific and optimal brain regions with pulsatile tissue signals to monitor such parameters.

FINDINGS

We validated the correspondence of these periodic signals with heart and breathing rates assessed using gold-standard electrodes in anaesthetised rodents. We extracted heart and breathing rates in sleeping rats and heart rate in rats moving freely in an arena. We also validated Physio-fUS imaging in sleeping human newborns using conventional ECG.

INTERPRETATION

We show the potential of fUS imaging as an integrative tool for simultaneously monitoring physiological parameters during neurofunctional imaging. Beyond the technological improvement, it could enhance our understanding of the link between breathing, heart rate and neurovascular activity in preclinical research and clinical functional ultrasound imaging.

FUNDING

This study was supported by the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement n°311025 and by the Fondation Bettencourt-Schueller under the program "Physics for Medicine".

Sunflower-like self-sustainable plant-wearable sensing probe

Powering and communicating with wearable devices on bio-interfaces is challenging due to strict weight, size, and resource constraints. This study presents a sunflower-like plant-wearable sensing device that harnesses solar energy, achieving complete energy self-sustainability for long-term monitoring of plant sap flow, a crucial indicator of plant health. It features foldable solar panels along with all essential flexible electronic components, resulting in a compact system that is lightweight enough for small plants. To tackle the low-energy density of solar power, we developed an ultralow-energy light communication mechanism inspired by fireflies. Together with unmanned aerial vehicles and deep learning algorithms, this approach enables efficient data retrieval from multiple devices across large agricultural fields. With its simple deployment, it shows great potential as a low-cost plant phenotyping tool. We believe our energy and communication solution for wearable devices can be extended to similar resource-limited and challenging scenarios, leading to exciting applications.

Monolithically Defined Wireless Fully Implantable Nervous System Interfaces

Evolution of implantable neural interfaces is critical in addressing the challenges in understanding the fundamental working principles and therapeutic applications for central and peripheral nervous systems. Traditional approaches utilizing hermetically sealed, rigid electronics and detached electrodes face challenges in power supply, encapsulation, channel count, dispersed application location, and modality. Employing thin-film, wirelessly powered devices is promising to expand capabilities. Devices that forego bulky power supplies, favoring a configuration where electronics are integrated directly onto thin films, reduce displacement volumes for seamless, fully implantable interfaces with high energy availability and soft mechanics to conform to the neuronal target. We discuss 3 device architectures: (1) Highly miniaturized devices that merge electronics and neural interfaces into a single, injectable format; (2) Interfaces that consolidate power, computation, and neural connectivity on a thin sheet applied directly to the target area; (3) A spatially dislocated approach where power and computation are situated subdermally, connected via a thin interconnect to the neural interface.Each has advantages and constraints in terms of implantation invasiveness, power capturing efficiency, and directional sensitivity of power delivery. In powering these devices, near-field power delivery emerges as the most implemented technique. Key parameters are size and volume of primary and secondary antennas, which determine coupling efficiency and power delivery. Based on application requirements, ranging from small to large animal models, subjects require system level designs. Material strategies play a crucial role; monolithic designs, with materials like polyimide substrates, enable scalability with high performance. This contrasts with established hermetic encapsulation approaches that use a stainless steel or titanium box with passthroughs that result in large tissue displacements and prohibit intimate integration with target organ systems. Encapsulation, particularly with parylene, enables longevity and effectiveness; more research is needed to enable human lifetime operation. Implant-to-ambient device communication, focusing on strategies compatible with well-established standards and off-the-shelf electronics, is discussed with the goal of enabling seamless system integration, reliability, and scalability. The interface with the central nervous system is explored through various wireless, battery-free devices capable of both stimulation (electrical and optogenetic) and recording (photometric and electrochemical). These devices show advanced capabilities for chronic studies and insights into neural dynamics. In the peripheral nervous system, stimulation devices for applications, such as spinal and muscle stimulation, are discussed. The challenges lie in the mechanical and electrochemical durability. Examples that successfully navigate these challenges offer solutions for chronic studies in this domain. The potential of wireless, fully implantable nervous system interfaces using near field resonant power transfer is characterized by monolithically defined device architecture, providing a significant leap toward seamless access to the central and peripheral nervous systems. New avenues for research and therapeutic applications supporting a multimodal and multisite approach to neuromodulation with a high degree of connectivity and a holistic approach toward deciphering and supplementing the nervous system may enable recovery and treatment of injury and chronic disease.