Evaluation of Brain Signal Amplifier Circuit Performance by Polymer Biosensor in Portable Neurological Patient Monitoring System

Abstract: Increasing the flexibility of electrodes by using flexible biocompatible biopolymer substrates as well as using conductive polymers with suitable electrical conductivity such as (PEDOT: PSS) instead of metallic base materials in the electrode channels has greatly contributed to this goal. But the next step is to increase the amplitude of the touched signal by the electrode in an amplifier circuit by suitable gain factor. Therefore, in the present study an electrical biosensor consisting of a 64-channel microelectrode with intra-structural amplification capability, external circuit precision for amplification of sensible brain signals on scale has been studied. Thereafter, the polymer biosensor to be integrated into a dry and portable monitoring system for monitoring neurologic disorders and identification of focal seizures symptoms e.g. in aura state for epilepsy. This has allowed by achieving a precise signal on scale even with a dry multichannel electrode, without no electrolyte gel between the surface of the electrode and the skin. Although, localization of the electrode is restricted, due to the importance of touching the prone signals in the frontal and partial lobes, it has been attempted to place the electrode on the frontal area to increase both signal sensibility and processing. Moreover, the error of muscle movements in frontal lobe is reduced by locating electrode in frontal-partial (FP) position to achieve a signal that overlapping both lobes to predicting seizure symptoms more accurately. This set-up has been successfully tested on patients, and along with the designed interface circuit, using an open-source oscillography application, signal touching has also been accomplished by an Android-based mobile phone.

Keywords: Brain Signal, Circuit Performance, Patient Monitoring, biosensor.