UART for Wearables (U4We): DC Power and Carrierless Signal Transfer over Conductive Textiles

Abstract

This brief presents a conductive-textile interconnection scheme for batteryless distributed wearable modules. Two conductive textile layers separated by an insulating fabric layer are used as a transmission line that simultaneously conveys DC power and pulse-based data signals without point-to-point wiring. To minimize the circuit overhead of each module, universal asynchronous receiver/transmitter (UART) pulses are directly coupled onto the textile through AC-coupling capacitors without carrier modulation. The textile waveform is modeled as the transient response of a second-order circuit, and design conditions for comparator-based waveform recovery and high-bitrate transmission are analytically derived. The resulting design framework determines whether a given combination of data rate, textile capacitance and resistance is feasible, and also provides the corresponding design range of the decoupling inductors. These results establish a basic methodology for textile-based simultaneous power and data transfer.