UC San Diego

The ability to sense forces is critical for ensuring that robots can safely interact with their environment. Nevertheless, there are numerous situations, particularly for medical applications, where environmental and sensor density requirements can pose challenges and constraints to sensor design and implementation. Our previous work presented a novel wireless force sensing paradigm and developed a force sensor based on wave backscattering. However, its large size, rigid design, and the need for an external power supply limited its practical use in medical applications. This work presents a significantly improved and miniaturized force sensor design with wireless and battery-free functions based on a new novel working principle. An end-to-end simulation of the proposed sensor, its fabrication, modeling, and experimental validations in a wired setting is presented. Then, flexible, wireless, and battery-free functions are added to the sensor by improving the sensor interfaces. The sensor performance in a wireless setting is evaluated, and the wireless communication quality is tested to validate the sensor’s suitability for medical applications. The proposed sensor can sense forces from 0 N to 6 N. In a wired setting, the sensor’s average Root Mean Square (RMS) error was 0.15 N and showed a resolution as high as 0.42 mN. In a wireless setting, the RMS error of the sensor was 0.21 N and had a resolution as high as 150 mN for our sensor prototypes with different interfaces. A demonstration of contact force sensing with the proposed sensors mounted on the body of a continuum robot and a phantom test is presented to show its potential to enable applications in fields such as medical robotics.