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Koschinski L, Lenyk B, Jung M, Lenzi I, Kampa B, Mayer D, Offenhäusser A, Musall S, Rincón Montes V. Validation of transparent and flexible neural implants for simultaneous electrophysiology, functional imaging, and optogenetics. J Mater Chem B 2023; 11:9639-9657. [PMID: 37610228 DOI: 10.1039/d3tb01191g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The combination of electrophysiology and neuroimaging methods allows the simultaneous measurement of electrical activity signals with calcium dynamics from single neurons to neuronal networks across distinct brain regions in vivo. While traditional electrophysiological techniques are limited by photo-induced artefacts and optical occlusion for neuroimaging, different types of transparent neural implants have been proposed to resolve these issues. However, reproducing proposed solutions is often challenging and it remains unclear which approach offers the best properties for long-term chronic multimodal recordings. We therefore created a streamlined fabrication process to produce, and directly compare, two types of transparent surface micro-electrocorticography (μECoG) implants: nano-mesh gold structures (m-μECoGs) versus a combination of solid gold interconnects and PEDOT:PSS-based electrodes (pp-μECoGs). Both implants allowed simultaneous multimodal recordings but pp-μECoGs offered the best overall electrical, electrochemical, and optical properties with negligible photo-induced artefacts to light wavelengths of interest. Showing functional chronic stability for up to four months, pp-μECoGs also allowed the simultaneous functional mapping of electrical and calcium neural signals upon visual and tactile stimuli during widefield imaging. Moreover, recordings during two-photon imaging showed no visible signal attenuation and enabled the correlation of network dynamics across brain regions to individual neurons located directly below the transparent electrical contacts.
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Affiliation(s)
- Lina Koschinski
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
- Helmholtz Nano Facility (HNF), Forschungszentrum, Jülich, Germany
- RWTH Aachen University, Germany
| | - Bohdan Lenyk
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
| | - Marie Jung
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
- RWTH Aachen University, Germany
| | - Irene Lenzi
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
- RWTH Aachen University, Germany
| | - Björn Kampa
- RWTH Aachen University, Germany
- JARA BRAIN Institute of Neuroscience and Medicine (INM-10), Forschungszentrum, Jülich, Germany
| | - Dirk Mayer
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
| | - Andreas Offenhäusser
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
| | - Simon Musall
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
- RWTH Aachen University, Germany
- University of Bonn, Faculty of Medicine, Institute of Experimental Epileptology and Cognition Research, Germany
- University Hospital Bonn, Germany
| | - Viviana Rincón Montes
- Institute of Biological Information Processing (IBI-3) - Bioelectronics, Forschungszentrum, Jülich, Germany.
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Chen GJ, Lin CM, Shih YH, Jian SR. The Microstructures and Characteristics of NiO Films: Effects of Substrate Temperature. Micromachines (Basel) 2022; 13:1940. [PMID: 36363961 PMCID: PMC9697434 DOI: 10.3390/mi13111940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/06/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
The influence of the substrate temperature on the structural, surface morphological, optical and nanomechanical properties of NiO films deposited on glass substrates using radio-frequency magnetron sputtering was examined by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Visible spectroscopy and nanoindentation, respectively. The results indicate that the substrate temperature exhibits significant influences on both the grain texturing orientation and surface morphology of the films. Namely, the dominant crystallographic orientation of the films switches from (111) to (200) accompanied by progressively roughening of the surface when the substrate temperature is increased from 300 °C to 500 °C. The average transmittance of the NiO films was also found to vary in the range of 60-85% in the visible wavelength region, depending on the substrate temperature and wavelength. In addition, the optical band gap calculated from the Tauc plot showed an increasing trend from 3.18 eV to 3.56 eV with increasing substrate temperature. Both the hardness and Young's modulus of NiO films were obtained by means of the nanoindentation continuous contact stiffness measurements mode. Moreover, the contact angle between the water droplet and film surface also indicated an intimate correlation between the surface energy, hence the wettability, of the film and substrate temperature.
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Affiliation(s)
- Guo-Ju Chen
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan
| | - Chih-Ming Lin
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yung-Hui Shih
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan
| | - Sheng-Rui Jian
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan
- Department of Applied Physics, National University of Kaohsiung, Kaohsiung 81148, Taiwan
- Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 80708, Taiwan
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Raji A, Lee Y, Baek S, Yoon J, Gasonoo A, Lee J, Lee J. The Effect of Reactive Sputtering on the Microstructure of Parylene-C. Materials 2022; 15:5203. [PMID: 35955139 PMCID: PMC9369700 DOI: 10.3390/ma15155203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/15/2022] [Accepted: 07/23/2022] [Indexed: 12/10/2022]
Abstract
Sputtering technique involves the use of plasma that locally heats surfaces of substrates during the deposition of atoms or molecules. This modifies the microstructure by increasing crystallinity and the adhesive properties of the substrate. In this study, the effect of sputtering on the microstructure of parylene-C was investigated in an aluminum nitride (AlN)-rich plasma environment. The sputtering process was carried out for 30, 45, 90 and 120 min on a 5 μm thick parylene-C film. Topography and morphology analyses were conducted on the parylene-C/AlN bilayers. Based on the experimental data, the results showed that the crystallinity of parylene-C/AlN bilayers was increased after 30 min of sputtering and remained saturated for 120 min. A scratch-resistance test conducted on the bilayers depicted that a higher force is required to delaminate the bilayers on top of the substrate. Thus, the adhesion properties of parylene-C/AlN bilayers were improved on glass substrate by about 17% during the variation of sputtering time.
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Sekhar MR, Laha R, Kar M. Tuning optical and optoelectronic properties of gold nanoparticle and ZnO thin film hetero-structures. Nano Ex 2020. [DOI: 10.1088/2632-959x/abd37e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Thin film hetero-structures (TFHSs) involving metal oxide thin films and noble metal nanoparticles are very important for many optoelectronics based device applications. This work reports the growth, characterization, and tuning of photoluminescence and I–V properties of TFHSs involving zinc oxide (ZnO) and gold nanoparticles (GNPs). ZnO thin films and GNPs were respectively deposited by the Pulsed Laser Deposition (PLD) and DC sputtering with subsequent annealing. Three different TFHSs were prepared by varying the relative positions of ZnO and GNPs, namely Si-GNPs-ZnO, Si-ZnO-GNPs, and Si-ZnO-GNPs-ZnO. X-ray diffraction results confirmed the high crystallinity of the films, with single phase nature of the ZnO and GNPs. Scanning electron microscopy micrograph analysis confirmed that the morphology of structures containing both GNPs and ZnO is influenced by the bottom layer. Diffuse reflectance spectroscopy results also indicated that the position of GNPs relative to ZnO affects the plasmon resonance of GNPs as well as the overall optical properties of the TFHSs. Photoluminescence studies revealed that the presence of GNPs affects the defect concentration in the TFHSs. The I–V characteristics showed that the TFHSs where ZnO contains GNPs in embedded form are better suited for photodiode application. This study adds a new dimension to the research on optoelectronics devices.
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