Design of a Compact Amplifier and Signal Conditioning Module for Wireless EEG Monitoring

Abstract

capable of being picked up on the surface of the scalp. The Abstract-Electroencephalogram (EEG) is an electrical recording of this potential is known as electroencephalogram recording of brain activity. It has numerous diagnostic and (EEG).research applications in the study of the brain. EEG can be recorded from the human brain by the placement of electrodes on the surface of the scalp, but the signals thus picked up are very cording of Ees ceran allengesrwhich small (on the order of a few microvolts) to be recorded or complicate the process of design of an amplifier for such digitized (for example by an A/D converter). Hence an signals; which include noise from external sources such as amplification system is required to amplify these small potentials power lines as well as those originating from the body itself to an acceptable level. Further, due to the small amplitude, these (such as ECG and other bio potentials). For useful recording signals are very susceptible to any background noise which could and interpretation of EEG, it is important that a relatively lowbe picked up by the human body through the ground path or the .. . ' .cables connecting the recording unit to the electrode. So, a signal nois which is free f tifactsi[1]. Ote conditioning circuit is required which is capable of filtering factors which could affect the performance of the amplifier are certain high and low frequency components of the input signal impedance, offset voltage and noise contribution due to the while allowing only the signal in the desired bandwidth to pass. electrode/skin interface.The complete block diagram for the circuit is shown in Figure 1.This paper discusses the design of a compact amplifier suitable The amplifier and signal conditioning module design described for this purpose and the considerations in the design of the in this paper includes an instrumentation amplifier, low-pass amplifier. One of the main concerns in the design of this new h amplifier was the need to make it compact and thus useful in and high pass filters for noise reduction and power isolation portable and wearable patient monitoring equipment. It also circuitry for reducing power instability which could lead to needs to be a low-power system in order to be able to power it noise being introduced in the power supply itself [2]. using batteries. The design presented here uses commercially available surface-mount components to ensure a low-cost design II. DESIGN CONSIDERATIONS with a relatively smaller footprint. The characteristics of the developed amplifier such Signal-to-Noise ratio, frequency A. Effects ofInterference response and gain are presented in this paper. Some of the measured EEG data is also presented.

Signal Conditioning provided by Sensitive Elements of Electric Bioimpedance Sensors

“…For biomedical applications, the major requirements of amplifiers that take voltages from biosensors is to convey signals from the millivolt range in the presence of DC voltages, to have a very high input impedance and a good rejection of common mode voltages [9]. This paper proposes for the input amplifier, a design with an instrumentation amplifier with input in the differential configuration [10]. Three operational amplifier design for instrumentation amplifier offers an elegant solution.…”