Thermally Induced Knudsen Forces for Contactless Manipulation of a Micro-Object

Abstract

In this paper, we propose that thermally induced Knudsen forces in a rarefied gas can be exploited to achieve a tweezer-like mechanism that can be used to trap and grasp a micro-object without physical contact. Using the direct simulation Monte Carlo (DSMC) method, we showed that the proposed mechanism is achieved when a heated thin plate, mounted perpendicularly on a flat substrate, is placed close to a colder object; in this case, a beam. This mechanism is mainly due to the pressure differences induced by the thermal edge flows at the corners of the beam and the thermal edge flow at the tip of the thin plate. Specifically, the pressure on the top surface of the beam is smaller than that on its bottom surface when the thin plate is above the beam, while the pressure on the right side of the beam is smaller than that on its left side when the thin plate is located near the right side of the beam. These differences in pressure generate a force, which attracts the beam to the plate horizontally and vertically. Furthermore, this phenomenon is enhanced when the height of the beam is shorter, such that the horizontal and vertical net forces, which attract the beam to the plate, become stronger. The mechanism proposed here was also found to depend significantly on the height of the beam, the temperature difference between the thin plate and the beam, and the Knudsen number.

A Cantilever-Based Piezoelectric MEMS for Arbitrary XY Path Generation

“…The actual micro-electro-mechanical systems (MEMS) fabrication capabilities fostered the deployment of new micro-devices for micro-object manipulation [1,2], micropositioning [3], energy harvesting [4], sensors [5], Lab-on-Chip [6], etc. Nowadays, the microand nano-machining developments allow to realize multi-hinge and multi-DoF MEMS devices.…”

A Piezoelectric MEMS Microgripper for Arbitrary XY Trajectory

“…Lately MEMS have undergone considerable development because of their applications in many fields: micropositioning [1], micro-object manipulation [2][3][4], Lab-on-Chip [5], sensors [6], and energy harvesting [7]. In particular, MEMS capable of making a body perform particular 2D trajectories have been used in: biological micro-/nanomanipulation [8,9], scanning probe microscopy based nanoimaging [10,11], micro-opto-electromechanical systems [12], etc.…”