Asymmetric Self Heating of Fully Printed Strain Gauge in Wheatstone Bridge Configuration

In the latest years, enabling technologies are leading the fourth industrial revolution that is still changing the industrial environment with the introduction of smart objects (SOs). Such context-aware devices have huge potential and applications such as predictive maintenance and continuous monitoring of different parameters. In this frame, the use of printed electronics and in particular Aerosol Jet Printing (AJP) allows embedding all the sensing and electronics directly onto the SOs, improving the metrological characteristics of the device, reducing the bulkiness of the sensing part as well as its impact on the final product. In this work, the effects of self-heating on AJP printed strain gauges is explored in order to evaluate the different related phenomena. The printed devices where at first characterized morphologically and electrically. Then different self-heating processes were evaluated considering different supply voltages both with simple strain gauges and Wheatstone bridges. It was possible to observe a temperature increase up to over 70°C on single device. On the other hand, it was possible to observe a thermal imbalance up to 0.5 °C on the different components of the Wheatstone bridge that produce a drift on the initial imbalance of the output voltage.