Disposable microscopic pumps have been patented by Berkeley Microinstruments
of Richmond, California (WO 97/25531).
A silicon chip 1 centimetre square is etched to form a tunnel 50 micrometres
high and wide and 8 millimetres long. The tunnel is capped with interlocking
“fingers” formed from piezoelectric material.
A low-voltage alternating current vibrates the fingers to create an
ultrasonic wave in any fluid in the tunnel. This pumps air through the tiny
tunnel at 30 millimetres a second and water at 0.3 millimetres a second.
The chip pump can be used for DNA-based diagnostic tests, or to detect
chemical warfare agents.
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