FILTER.

摘要

PCT No. PCT/GB86/00334 Sec. 371 Date Apr. 1, 1987 Sec. 102(e) Date Apr. 1, 1987 PCT Filed Jun. 11, 1986 PCT Pub. No. WO86/07284 PCT Pub. Date Dec. 18, 1986.A filter which is particularly useful with biological material is formed of porous piezoelectric material such as PZT or Polyvinylidene fluoride. By an application of a voltage to the piezoelectric material, the filter body is caused to vibrate so as to inhibit fouling. In a modification, the piezoelectric material is not itself porous but is bonded to a filter membrane such that vibrations of the piezoelectric material are transmitted to the membrane. Through suitable control of the vibration, the selectivity of the filter can be controlled. In other modifications the vibratory movement of the filter membrane can be produced in other ways such as electro-mechanically.