A Simple and Portable Preamplifier for Multichannel Intracortical Recordings Using Commercial Components

Simple and useful methods are described herein for a portable and multichannel preamplifier circuit. These procedures include mainly operational amplifier selection, offset voltage reduction, active guarding circuit, selectable reference node, and grounded plate arrangement. A fabricated six-channel board for intracortical activities recording using commercial components measures 4.0 cm times 8.5 cm, weighs 83 g, consumes up to 24.5 mW, and estimates 1.3 U Vrms input-referred noise, with the gain of 39.4 dB. The material of entire six-channel preamplifier costs less than 24.5 United States dollars. The preamplifier has been successfully utilized in vivo to process cortically derived extracellular evoked potentials under anesthetized rat. Results from both simulated circuit testing and practical animal measuring indicate that a high-quality recording can be obtained by adopting the presented circuits. The proposed preamplifier can be easily expanded by combining other post-processing circuits or recording devices. This preamplifier can also be flexibly modified and applied to other related electrophysiological or physiological studies.