Micromachined membrane particle filters

Abstract

We report herr several particle membrane filters (8 x 8 mn2) with circular, hexagonal and rectangular through holes. By varying hole dimensions from 6 to 12 pm, opening factors from 4 to 45 ?4 arc achieved. In order to improve the filter robustness, a composite silicon nitridelparylene membrane technology is developed. More importantly, fluid dynamic performance of the filters is also studied by both experiments and numerical simulations. It is found that the gaseous flow through the filters depends strongly on opening factors, and the measured pressure drops are much lower than that from numerical simulation using the Navier-Stokes equation. Interestingly, surface velocity slip can only account for a minor part of the discrepancy. This suggests that a very interesting topic for micro fluid mechanics research is identified.

A Combined Continuum/DSMC Technique for Multiscale Analysis of Microfluidic Filters

“…In [2], microfluidic filters were developed to capture airborne particles for detailed chemical analysis. The filters were fabricated by opening an array of holes on thin silicon membranes.…”

“…The membrane thickness was 1 µm and a typical filter or hole size, determined by the minimum size of the particles to be filtered, ranged from 5 to 10 µm. Figure 1 shows the cross-sectional images of the filters fabricated in [2]. When the filters shown in Fig.…”

“…Prediction of gas flow through microfluidic devices is important to enable the design and development of complex microelectromechanical systems (MEMS) [1][2][3][4]. Simulation of gas flow through microfluidic devices is, however, very complicated because of the breakdown of continuum theories.…”

Plasma removal of Parylene C

“…The use of Parylene C as a structural material in microelectromechanical systems (MEMS) devices and in particular bioMEMS and microfluidics has gained traction [6][7][8][9][10]. Among the many polymers used as structural materials, Parylene C is an increasingly popular choice due to its deposition method, low process temperature, transparency and compatibility with standard microfabrication processes [11].…”

Solvent-free surface modification by initiated chemical vapor deposition to render plasma bonding capabilities to surfaces

“…The integrity of bond strength was studied by coating various substrate materials with V3D3, including a porous PTFE membrane, and integrating them into PDMS microfluidic devices and burst pressure testing them. Burst pressure is an important parameter for microfluidic network design and has been reported in other studies of microfluidic networks (Chen et al 2009;Satyanarayana et al 2005;Yang et al 1999); knowledge of this data will enable developers to use a deterministic approach when selecting the appropriate materials and manufacturing process for a microfluidic device. The ability to successfully bond porous PTFE membranes was an important focus of this work because it can enable selective mass transport control (Chueh et al 2007).…”