Biology subjects

Pinto, J. V.

Publications and source records attributed to Pinto, J. V..

3 recordsLinked to original sources

bioRxiv2023

Patterned Metal Grids for Flexible and Transparent Neural Microelectrode Arrays

Flexible and transparent microelectrodes can provide large-scale neural recordings with temporal and spatial resolution when used alongside functional calcium imaging. Patterned metal grids defined by direct laser writing (DWL) are a promising approach for these electrodes, as they resort to standard microfabrication processes and materials, allowing the possibility of mass production. For these reasons, a study exploring transparent grid-based electrodes using DWL for measuring electrocorticography signal was performed. Patterned metal grids with 1 m of linewidth and 22 m of spacing between lines showed a sheet resistance of 6 {Omega}/sq and a transmittance of 81% at 550 nm. The grids were transferred to a 5 m Parylene-C membrane using an optimized procedure that involves an oxygen plasma pre-treatment. This procedure ensures mechanical robustness and stability of the grids. Finally, a flexible and transparent prototype was fabricated with a microelectrode array composed by 16 electrodes with 500 m of diameter. These microelectrodes shown an impedance of 10 k{Omega} at 1 kHz in saline solution and they are highly conformal facilitating in vivo implantation and the recording of neural activity in the mouse cerebellum surface. To conclude, patterned metal grids based-electrodes exhibit a promising performance compared to transparent conductive oxides or graphene. Moreover, the introduction of DLW enables easy and fast manipulation of grid shape and dimensions without the need of physical masks, while keeping large scale compatibility, which is important for tools used in neuroscience community.

neuroscience↗

bioRxiv2020

Transparent and flexible ECoG electrode arrays based on silver nanowire networks for neural recordings

This work explored hybrid films of silver nanowires (AgNWs) with indium-zinc oxide (IZO) for developing high-performance and low-cost electrocorticography (ECoG) electrodes. The transparent hybrid films achieved a sheet resistance of 6 {Omega}/sq enabling electrodes with 500 m diameter to reach an impedance of 20 k{Omega} at 1 kHz and a charge storage capacity of 3.2 mC/cm2, an improvement in properties over IZO electrodes, whose performance is on par with the classical tin doped indium oxide (ITO). Characterization of light-induced artifacts was performed showing that light intensities <14 mW/mm2 elicit minimal electrical potential variation, which falls within the magnitude of baseline noise. The validation of electrodes in vivo was achieved by recording electrical neural activity from the surface of rat cortex under anaesthesia. Moreover, the presence of the hybrid films did not cause distortion of light during fluorescence microscopy. This study highlighted the capabilities of the hybrid structure of AgNWs with IZO, that can be fabricated with industrially-established processes at low cost, to be used for transparent ECoG electrodes, offering a new way to record neural electrical activity on a large and fast scale with direct visualization of neurons.

neuroscience↗

bioRxiv2016

Promiscuity of peripheral molecular biomarkers in major psychiatric disorders: a transdiagnostic systematic review

The search for biomarkers has been one of the leading endeavors in biological psychiatry; nevertheless, in spite of hundreds of publications, it has yet to make an impact in clinical practice. To study how biomarker research has progressed over the years, we performed a systematic review of the literature to evaluate (a) the most studied peripheral molecular markers in major psychiatric disorders, (b) the main features of studies in which they are proposed as biomarkers and (c) whether their patterns of variation are similar across disorders. Out of the six molecules most commonly present as keywords in articles studying plasmatic markers of schizophrenia, major depressive disorder or bipolar disorder, five (BDNF, TNF-alpha, IL-6, C-reactive protein and cortisol) were the same across the three diagnoses. An analysis of the literature on these molecules showed that, while 65% of studies were cross-sectional and 66% compared biomarker levels between patients and controls in specific disorders, only 10% presented an objective measure of diagnostic or prognostic efficacy. Meta-analyses showed that variation in the levels of these molecules was robust across studies, but also similar among disorders, suggesting them to reflect transdiagnostic systemic consequences of psychiatric illness rather than diagnostic markers. Based on this, we discuss how current publication practices have led to research fragmentation across diagnoses, and what steps can be taken in order to increase clinical translation in the field.

neuroscience↗