Balancing Fully Printed Strain Gauges for Full Wheatstone Bridges

Smart Objects (SOs) are increasingly pervasive thanks to new enabling technologies that facilitate the generation of added value through embedded sensors in existing objects. To embed those sensors, 3D-printed electronic technology emerges as a promising solution. However, these technologies encounter challenges regarding their production variability that can affect both the morphological characteristics of the sensors as well as their metrological performance. To mitigate such metrological issues, this paper proposes a method to design fully printed Wheatstone bridges with balancing capabilities using a set of printed trimmers. Such devices are theoretically modelled and simulated to provide a general understanding the device behavior. Then a set of devices were produced and tested to verify both in a standalone and in a bridge architecture. The experiments showed that the proposed model is reliable and that the modified Wheatstone bridges improved the yield up to 90% reducing the bridge imbalance up to three orders of magnitude to reach a sub-millivolt one.