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S. Vollebregt

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2 records found

Conference paper (2020) - A.I. Velea, S. Vollebregt, G.K. Wardhana, V. Giagka
This paper reports on the characterization of a microfabricated wafer-scale, graphene-based, soft implant for spinal cord applications. Graphene is used because of its high transparency and good conductivity, making it suitable for optogenetic applications. Moreover it has a high mechanical strength and is potentially biocompatible. The implant consists of multi-layered chemical vapor deposited graphene, in the form of electrodes and tracks, encapsulated between 2 layers of silicone. Methods such as Raman spectroscopy, optical transmittance, and electrical measurements combined with bending tests and in-vitro experiments, using phosphate-buffered saline (PBS) solution, were employed to characterize the device. The results have shown high bendability and no critical damage of the graphene after immersing the device in PBS solution up to 7 days. To the authors' best knowledge, this is the first work that presents a soft and fully scalable optogenetics-compatible graphene-based spinal cord electrode array. ...
Conference paper (2020) - B.T. Buijtendorp, J. Bueno, D.J. Thoen, V. Murugesan P.M. Sberna, J.J.A. Baselmans, S. Vollebregt, A. Endo
Superconducting resonators used in millimeter-submillimeter astronomy would greatly benefit from deposited dielectrics with a small dielectric loss. We deposited hydrogenated amorphous silicon films using plasma-enhanced chemical vapor deposition, at substrate temperatures of 100°C, 250°C and 350°C. The measured void volume fraction, hydrogen content, microstructure parameter, and bond-angle disorder are negatively correlated with the substrate temperature. All three films have a loss tangent below 10−5 for a resonator energy of 105 photons, at 120 mK and 4–7 GHz. This makes these films promising for microwave kinetic inductance detectors and on-chip millimeter-submilimeter filters. ...