If you want to measure the reaction force of an insect’s leg, it would be unwise to push it with your finger; the difference in size between the two is too great to be sensitive enough. However, a set of soft machine microfingers controlled by the hand can now do the job. Created by scientists at Ritsumeikan University in Japan, this kit is only 12 mm long, 3 mm wide and 490 microns (millionths of a meter) thick per flat, rectangular device.
Five of these sensors are integrated into a single device to build a robotic hand with soft, flexible fingers, each containing a balloon-like pneumatic actuator, and a liquid metal strain gauge.
Users wear special sensors on their fingers that measure the speed, degree, and direction of their finger-bending movements. This data is relayed to the corresponding microfingers in real time, causing them to bend accordingly. If they press against an object, the strain gauge measures the force of that object.
A diagram illustrating how microfingers can be used to measure reaction forces in the legs of a ball mouse woman
In tests of the technique, the microfinger was used to measure the reaction force on the leg of a live ball mouse woman (the watermelon bug we used to play with as children), which was held upside down by a suction tool, and the force on its leg was measured to be about 10 milliNewtons, which is consistent with previously calculated estimates. The scientists hope that this technique will be further developed not only for insect research but also for other applications that require small-scale “hands-on” methods.
Lead scientist Professor Satoshi Konishi said, “With our strain-sensing microfingers, we were able to directly measure the propulsive motion and force of the legs and torso of the insects – something that was not possible before. We anticipate that our results will allow further technological developments in microfinger-insect interactions, leading to smaller-scale human-environment interactions.”
A paper on this research was recently published in the journal Scientific Reports.
