Abstract
Highly sensitive, wide-measurement-range compact load sensors are desirable for various applications. A load sensor using an AT-cut quartz crystal resonator (QCR) has superior characteristics such as, high accuracy, improved strength under compressive stress, long-term stability. However, a retention mechanism is required to firmly support the QCR because the QCR is easily broken by stretching and bending motions. Conventional machining processes are not suitable for further miniaturization of the sensor. Even if the retention mechanism were miniaturized, the assembly process is complicated. We proposed a μQCR load sensor that fabricated by microfabrication and bonding for simplifying assembly process. The objective of this study is to improve the maximum load and load-measurement resolution of the sensor for application to biological signal detection in the bed. We fabricated a μQCR sensor with a sensitivity of 374 Hz/N (theoretical maximum load is 130 N) and succeeded in detecting multiple biological signals (respiration, heartbeat, and posture).
