Voltage-based balancing technique for half printed Wheatstone bridges

The Wheatstone bridge is a fundamental circuit in resistive sensing systems, widely used for converting small resistance changes into measurable voltage signals. As the demand for smart, flexible, and scalable electronic systems grows, printed electronics technologies are increasingly adopted for sensor fabrication. These techniques enable direct deposition of conductive inks on various substrates, making them ideal for applications in wearable electronics, soft robotics, and structural health monitoring. Printed strain gauges are promising due to their simplicity and compatibility with flexible substrates. However, the high resistance tolerance introduced by the printing process remains a significant challenge. Traditional solutions involve manual trimming or precision components, which are not practical for scalable and easily deployable systems. This work presents a novel measurement method designed for printed strain gauges with high resistance tolerance, applied to a practical case involving a half Wheatstone bridge. The initial resistance mismatch of the printed strain gauges is compensated by adjusting a single controllable reference voltage, eliminating the need for trimming or complex circuities. The proposed method was experimentally validated with printed strain gauges on a steel cantilever beam, achieving a linearity error of less than 5%/FS (with FS = 0.018%) and a negligible offset less than 21 µV. By compensating for the initial offset caused by resistance mismatch through the adjustment of the bridge reference voltages, the proposed method preserves signal linearity and enables an effective operation of the subsequent cascaded amplification stage, thereby enhancing the overall performance of printed sensor systems.