MEMS microfilter with acoustic cleaning

This paper reports the design, fabrication, and testing of a new MEMS microfilter developed from a flexural plate wave (FPW) device in which acoustic forces generated within the filter membrane act to free particles and sweep them away from clogged pores. MEMS devices have already been shown to be effective for absolute filtration, but clogging has made them impractical for most applications. Also previously shown was the ability of flexural plate wave (FPW) devices to move particles in a pumped liquid. Recognizing the FPW pumping as a self-cleaning mechanism for microfilters presents exciting possibilities for reduced filter fouling, allowing larger volumes of fluid to be filtered and extending filter lifetime. Both the filtered fluid and the collected large particles could be the useful output. Acoustic particle manipulation has now been shown to free 2 and 10 /spl mu/m diameter spheres and sweep them away from once-blocked pores in both 4 /spl mu/m and 8 /spl mu/m filters. Experiments were performed with deionized (DI) water and polystyrene spheres.