An Adaptive Readout Circuit for e-Textile Pressure Sensor: Design and Evaluation

Piezoresistive e-textile pressure sensors exhibit large variability in resistance due to differences in sensor geometry, material properties, and applied load, which complicates stable analog readout and limits the effective use of analog-to-digital converters (ADCs). This paper presents an adaptive readout architecture that addresses this challenge by dynamically regulating the voltage-divider interface between the sensor and the readout circuitry. The proposed system employs a digitally adjustable resistance controlled by a feedback algorithm that continuously maintains the sensor output within a predefined ADC operating range. By adapting the readout resistance in response to changes in sensor resistance, the architecture prevents voltage saturation, and avoids the need for fixed-gain amplifiers or analog multiplexing stages. The approach supports array-based sensing through column-wise adaptive conditioning and sequential scanning. Experimental evaluations using Velostat-based pressure sensors demonstrate stable operation across multiple sensor sizes, consistent voltage–force characteristics under varying loads, and reliable acquisition up to 200 Hz.