MEMS-Based Micro Sensors for Measuring the Tiny Forces Acting on Insects

Abstract

Small insects perform agile locomotion, such as running, jumping, and flying. Recently, many robots, inspired by such insect performance, have been developed and are expected to be smaller and more maneuverable than conventional robots. For the development of insect-inspired robots, understanding the mechanical dynamics of the target insect is important. However, evaluating the dynamics via conventional commercialized force sensors is difficult because the exerted force and insect itself are tiny in strength and size. Here, we review force sensor devices, especially fabricated for measuring the tiny forces acting on insects during locomotion. As the force sensor, micro-force plates for measuring the ground reaction force and micro-force probes for measuring the flying force have mainly been developed. In addition, many such sensors have been fabricated via a microelectromechanical system (MEMS) process, due to the process precision and high sensitivity. In this review, we focus on the sensing principle, design guide, fabrication process, and measurement method of each sensor, as well as the technical challenges in each method. Finally, the common process flow of the development of specialized MEMS sensors is briefly discussed.

Ultrasensitive piezoelectric sensor based on two-dimensional Na2Cl crystals with periodic atom vacancies

“…A wingbeat frequency of ~5 Hz was obtained (Supplementary Fig. 12c), which is consistent with the results from other studies on apping frequency 44 .…”

“…43 , re ects sensitive dependence on an initial condition, with extremely small signals leading to extraordinarily large responses. To our knowledge, the air ow variation caused by a apping butter y has not been well measured because the variation is quite small 44 . Using the presented sensor, the open-circuit voltage response to the air ow variation at a 5 cm distance from a apping butter y was obtained, and the movement of the butter y and the real-time motoring of voltage response were shown in the movies (Supplementary Video 1).…”

In‐flight force estimation by flight mill calibration

“…Measuring in‐flight forces of any flying animal is challenging, due to the difficulty in fixing them to a sensing device, and the small forces produced by insects in particular amplify these challenges. Direct interrogation of forces using classical force sensors can be accomplished with micro‐electro‐mechanical (MEMS) devices with resolutions on the order of newtons (Takahashi, 2022). However, the physical size of such sensors can be on the order of the insect itself, on the order of 1–5 mm, and may require the use of a wind tunnel rather than a flight mill in order to eliminate the need for bridging electrical connections across a rotating joint.…”

Thin Glass Micro Force Plate Supported by Planar Spiral Springs for Measuring Minute Forces

“…In recent years, sensors capable of measuring with a high resolution of μN or less have been extensively developed [ 1 , 2 , 3 , 4 ]. One of the motivations for developing such sensors is the observation of the behavior of living cells and tiny forces generated by small animals [ 5 , 6 ]. Among these sensors, micro force plates are widely used as powerful tools for measuring insect ground reaction force (GRF) or microdroplet collision force [ 7 , 8 , 9 , 10 , 11 ].…”