Micro-electro mechanical systems (MEMS) accelerometer has been implemented in various applications across industries. To expand its application to textiles, here we propose a facile fabrication and packaging method for fiber-shaped flexible MEMS thermal accelerometer. The sensing structure was fabricated through a standard microfabrication process on a thin polyimide film substrate. The film was then cut into stick shape and packaged inside a flexible resin tube through a facile insertion process. A sensitivity improvement strategy by mitigating the thermal mass around the sensing structure was also introduced. Gravitational acceleration measurement using the proposed sensors was demonstrated using an inclination stage. Finally, measurement of human hand movement using the proposed sensors was demonstrated.

Respiration and heartbeat are among the important vital signs of living beings. Taking advantage of the physical attachment of lung and heart, measurements of both can be performed simultaneously using airflow rate microsensors to measure the respiration airflow. For such airflow rate sensors, the packaging is crucial to define and encapsulate the airflow region. In this study, we propose a facile packaging technique for flexible airflow rate microsensor. The thermal calorimetric sensing structure was fabricated through a standard microfabrication technology on a thin polyimide film. The film was packaged at the center of a resin tube utilizing its buckling. We also proposed an approach to improve the time response by limiting the thermal capacity around the sensing structure through the implementation of a thin substrate for the sensing structure supported by a thicker film. The strategy successfully improved both the time response and sensitivity of the airflow rate sensor. Finally, the utilization of the sensor for simultaneous respiration and heartbeat measurement was demonstrated through an animal experiment using a small animal, namely rat.