Soft Microgripping Using Ionic Liquid Droplet for High Temperature and Vacuum Applications

Aqueous droplet-based micro-gripper has been used for micro-assembly. However they cannot be used for high temperature and vacuum applications. Ionic liquids, organic salts that have a lower melting point temperature, appear suitable for droplet-based micro-gripping application in high temperature and vacuum environments because of their nonvolatility and thermal stability. In this paper, we demonstrated the use of ionic liquid as the operating liquid for micro-gripping applications in high temperatures (up to 110 °C) and vacuum (up to 24 inch Hg) environments. Electrowetting was utilized to dynamically change the contact angle of a 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) liquid bridge to control the capillary lifting forces. The lifting force generated by the liquid bridge was experimentally characterized. The range of capillary lifting forces can be adjusted by changing the liquid bridge height and droplet volume to pick up and release objects with different weights. The dynamic response of the BmimPF6 liquid bridge was also characterized