Abstract
In order to reduce the impedance and improve in vivo neural recording performance of our developed Michigan type silicon electrodes, rough-surfaced AuPt alloy nanoparticles with nanoporosity were deposited on gold microelectrode sites through electro-co-deposition of Au-Pt-Cu alloy nanoparticles, followed by chemical dealloying Cu. The AuPt alloy nanoparticles modified gold microelectrode sites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and in vivo neural recording experiment. The SEM images showed that the prepared AuPt alloy nanoparticles exhibited cauliflower-like shapes and possessed very rough surfaces with many different sizes of pores. Average impedance of rough-surfaced AuPt alloy nanoparticles modified sites was 0.23 MΩ at 1 kHz, which was only 4.7% of that of bare gold microelectrode sites (4.9 MΩ), and corresponding in vitro background noise in the range of 1 Hz to 7500 Hz decreased to 7.5 from 34.1 at bare gold microelectrode sites. Spontaneous spike signal recording was used to evaluate in vivo neural recording performance of modified microelectrode sites, and results showed that rough-surfaced AuPt alloy nanoparticles modified microelectrode sites exhibited higher average spike signal-to-noise ratio (SNR) of 4.8 in lateral globus pallidus (GPe) due to lower background noise compared to control microelectrodes. Electro-co-deposition of Au-Pt-Cu alloy nanoparticles combined with chemical dealloying Cu was a convenient way for increasing the effective surface area of microelectrode sites, which could reduce electrode impedance and improve the quality of in vivo spike signal recording.
Highlights
In vivo neural recording provides a useful method for neuroscientists to understand the basic organization and operation of the nervous system, and especially the electrophysiological changes caused by neurological disorders such as Parkinson’s disease [1,2,3,4,5] and Alzheimer’s disease [6]
With mechanical systems (MEMS) technology, the precise definition of electrode size and shape can be realized, and multiple recording/stimulation sites can be fabricated on a single probe shank [9]
Starting with the pioneering work from Wise et al [10], a growing number of silicon-based electrode arrays have been developed in the past and the performances of MEMS silicon microelectrodes have been improved in many aspects [11,12], e.g., three-dimensional arrays [13,14,15], dual-sided microelectrode arrays [16], integrated electronics or microfluidic channels [17,18,19,20,21,22], silicon probes for optical stimulation and imaging [23,24,25,26,27,28] or neurochemical signals detection [29,30,31]
Summary
In vivo neural recording provides a useful method for neuroscientists to understand the basic organization and operation of the nervous system, and especially the electrophysiological changes caused by neurological disorders such as Parkinson’s disease [1,2,3,4,5] and Alzheimer’s disease [6]. microwire-based electrodes have been a versatile tool for neuroscientists for decades, the limitations of microwire-based electrodes, such as difficult implantation, low spatial resolution, low reproducibility and manual construction are well known [7,8]. With MEMS technology, the precise definition of electrode size and shape can be realized, and multiple recording/stimulation sites can be fabricated on a single probe shank [9]. Starting with the pioneering work from Wise et al [10], a growing number of silicon-based electrode arrays have been developed in the past and the performances of MEMS silicon microelectrodes have been improved in many aspects [11,12], e.g., three-dimensional arrays [13,14,15], dual-sided microelectrode arrays [16], integrated electronics or microfluidic channels [17,18,19,20,21,22], silicon probes for optical stimulation and imaging [23,24,25,26,27,28] or neurochemical signals detection [29,30,31]. Q noise level was computed in the form of root mean square Vrms , which
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