Development and analysis of electrocardiography circuit on flexible polymers

Abstract

Recently, flexible printed circuit (FPC) technology is utilized in electronic industry to reduce the device size and weight. Electrocardiography (ECG) device is one of the healthcare devices needed in small size as to give comfort to user. There are various technique of fabricating circuit on flexible substrate were proposed such as etching, screen printing, and inkjet printing. However, the conductive traces fabricated using those techniques were easily cracked and led to loose of circuit continuity. Thus, the aim of this study is to find the best flexible material to be used with copper tape as conductive traces to replace the method of using nano-scale particle material. ECG circuit is integrated and fabricated on flexible substrate material using vinyl cutting technique. There were three different materials chosen to be used in this study; silicone rubber sheet, Thermoplastic Polyurethane (TPU) and Polyethylene Terephthalate (PET). Material characterization analysis such as Atomic Force Microscopy (AFM), contact angle and peel adhesion test were done on these materials to know the best material suit to be used with conductive copper tape (Copper tape 1181 from 3M). From that, this study has found that PET is the most suitable material to be used because its peel adhesion strength is the highest. Then, ECG circuit was developed using vinyl cutting technique and the circuit performance between flexible substrate and rigid substrate were compared. In the data processing stage, ECG data were denoised using sym20 from Wavelet Transform tool in MATLAB. Signal to noise ratio (SNR) parameter was calculated and used as the signal quality indicator. The data then further analyzed using statistical ANOVA to determine the significant features. Results showed that vinyl cutting method is a successful method to fabricate circuit on PET substrate as the performance of the flexible ECG circuit is comparable with rigid ECG circuit.