Pinch Force Measurement Using a Geomagnetic Sensor

Hand muscle strength, such as grip strength, pinch strength, and holding strength is an important indicator when determining hand diseases, treatment, and rehabilitation methods. However, pinch measurement devices for one type of hand muscle strength are expensive and primarily for medical purposes, so the general public does not typically use them. In this study, we propose a pinch measurement method that uses only a smartphone and a measurement device with an embedded magnet. We created a measurement device in which the magnet position changes when force is applied. We also used a magnetic sensor built into a smartphone to estimate pinch force based on the amount of change in the magnetic field from the distance between the magnet and the smartphone. Magnetic fields can be easily obtained from existing applications. This makes it possible to routinely measure pinch force using an inexpensive measuring device rather than a conventional pinch measuring device.