Dynamic study of the gate of an n-MOS microfluidic transistor for computational microfluidics

This paper reports for the first time the concept of maximum working frequency of the nMOS microfluidic transistor, commenting the importance of this value on the operation of the device for computational microfluidics. The main component of the microfluidic transistors is the gate, that is, the structure where the actuation takes place. For nMOS microfluidic transistors, this part is a microstructure which includes two membranes, namely, a small membrane and large membrane, linked each other by a column. The natural frequencies of the gate have to be known in order to avoid undesired behaviors. In this paper, a numerical dynamic analysis using Finite Element Method is performed in order to obtain the natural frequencies of this kind of structures, and specially the effects of those results in the whole behavior of the nMOS microfluidic transistor. The study is performed using the parameters of a fabricated microfluidic transistor, where the microstructure of the gate was correctly designed using SU-8 as material. The results show the first natural frequencies at about 4.15 kHz. This value is proposed as maximum working frequency of that particular microfluidic transistor.