Heat Transfer Scale Effect Analysis and Parameter Measurement of an Electrothermal Microgripper

Abstract

An electrothermal microgripper is an important actuator in microelectromechanical and micro-operating systems, and its temperature field analysis is the core problem in research and design. Because of the small size of an electrothermal microgripper, its microscale heat transfer characteristics are different from those of the macrostate. At present, only a few studies on the heat transfer scale effect in electrothermal microgrippers have been conducted, and the heat transfer analysis method under the macrostate is often used directly. The temperature field analysed and simulated is different from the actual situation. In the present study, the heat transfer mechanism of an electrothermal microgripper in the microscale was analysed. The temperature field of a series of microscale heating devices was measured using microthermal imaging equipment, and the heat transfer parameters of the microscale were fitted. Results show that the natural convective heat transfer coefficient of air on the microscale can reach 60–300 times that on the macroscale, which is an important heat transfer mode affecting the temperature field distribution of the electrothermal microgripper. Combined with the finite element simulation software, the temperature field of the electrothermal microgripper could be accurately simulated using the experimental microscale heat transfer parameters measured. This study provides an important theoretical basis and data support for the optimal design of the temperature controller of the electrothermal microgripper.

Coupled Finite Element-Finite Volume Multi-Physics Analysis of MEMS Electrothermal Actuators

“…All the above reinforce the fact that the assumption of a constant heat transfer coefficient that one would apply in macro-modelling (say, 25 pW/µm 2 •K, as in [14]) or a constant heat loss is not an entirely correct assumption and although perhaps not so detrimental under conditions involving merely natural convection in air, it may be an issue with either other media or other medium conditions, such as different flow rates or even highly temperature-sensitive drivers. The claim that a constant heat transfer coefficient (in particular, 25 pW/µm 2 •K, which is typically employed for natural convection in air at the macroscale) is not ideal for microscale devices is also supported by the work undertaken in [37], where it was hypothesised that the convection heat transfer coefficient may in fact reach values of orders of magnitude larger than that for larger-scale macro-objects. With the use of the two-way system coupling methodology, such larger coefficients are captured here.…”

Manipulation of Miniature and Microminiature Bodies on a Harmonically Oscillating Platform by Controlling Dry Friction

“…Therefore, a frictional asymmetry is created by such dynamic dry friction control. The harmonic signal for the electrodynamic shaker is amplified by a power amplifier (LV-103, Metra Mess-und Frequenztechnik in Radebeul, Radebeul, Germany) (6). The signal for the piezoelectric actuator is amplified by a piezo linear amplifier (EPA-104, Piezo Systems Inc., Cambridge, MA, USA) (7).…”

“…The efficiency of manipulation and assembly of miniature and microminiature components currently are of great concern to various industries related to microtechnologies. For manipulation of miniature and microminiature bodies, a variety of techniques are used, ranging from prehensile pick and place techniques [1][2][3][4][5][6] to nonprehensile methods such as vibration-assisted manipulation [7][8][9]. However, prehensile techniques such as picking always have some mechanical effect on the body; besides, due to various shapes of the miniature and microminiature bodies being manipulated or assembled, microgrippers must be changed frequently when pick and place operations are used.…”