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A flexible wireless electrocardiogram (ECG) device, integrated with fabric was fabricated for monitoring physiological signals in wearable biomedical applications. The ECG device consists of dry electrodes and a readout module. The dry electrode was fabricated by depositing multi-walled carbon nanotube (MWCNTs)/polydimethylsiloxane (PDMS) composite on a thermoplastic polyurethane (TPU) substrate with screen printed silver (Ag) layer. The readout module with wireless data transmission capability was designed and fabricated on a flexible polyimide substrate. The ECG device was attached to fabric, and its performance was investigated by measuring the ECG signals and comparing them with the results of conventional wet Ag/AgCl electrode. It was observed that the device demonstrated similar performance in terms of signal intensity and correlation when compared to the conventional wet ECG electrodes. Signal-to-noise-ratio (SNR) analysis clearly showed that the dry electrodes with an average SNR of 23.1 dB, perform better than the commercially available Ag/AgCl electrodes (SNR of 21.2 dB). In addition, the capability of the fabric based dry electrodes to measure ECG signals during the physiological activities under exercise motions was studied. This enabled understanding the effect of motion artifacts on the dry electrode response and allowed comparing the obtained ECG signals with the responses of conventional wet ECG electrodes (subjected to similar conditions). It was observed that, even though dry electrodes didn’t use any kind of adhesive gel for measuring the ECG signals, they performed very similar to conventional wet electrodes. The results obtained clearly demonstrated the feasibility of employing fabric based flexible dry ECG electrodes for continuous monitoring of ECG signals in health care applications and can potentially replace the wet electrodes.

Design and rapid prototyping of a tunable and compact microstrip antenna for industrial, scientific and medical (ISM) band applications is presented in this paper. Laser machining is introduced as a fast and accurate method for the antenna fabrication. The antenna, with an overall dimension of $65\times 46\times0.127$ mm, was fabricated by sandwiching a flexible Kapton polyimide substrate, with a dielectric constant of 3.5, between two flexible copper tapes, as the radiating patch and ground plane, respectively. The radiating patch was patterned in a meander configuration, with three slots, demonstrating the capability to reduce the resonant frequency of the microstrip antenna from 2.4 GHz to 900 MHz, without increasing the overall size of the antenna (87% compact). The effect of mechanical stress on the antenna performance was investigated by performing bend and stretch tests. The antenna was subjected to compressive bend with a minimum radius of curvature of 86 mm and 150 mm along the x-axis and y-axis which resulted in a maximum increase of resonant frequency by 3.1% and 1.3%, respectively. Similarly, the antenna was subjected to tensile bend with a minimum radius of curvature of 79 mm and 162 mm along the x-axis and y-axis which resulted in a maximum decrease of the resonant frequency by 4.2% and 0.3%, respectively. An overall 0.9% decrease in the resonant frequency was measured for an applied strain of 0.09% during stretching the antenna along the y-axis.