A pyroelectric-piezoelectric valve for integrated microfluidics

A low-voltage, low-power microvalve that can be actuated either electrically using the inverse piezoelectric effect or thermally using the pyroelectric effect is presented here. The value consists of external laser-machined bulk piezoelectric unimorph actuators mechanically linked to surface micromachined nickel cap structures anchored on silicon nitride membrane tethers. A self-aligned mechanical linking process for the assembly of external bulk piezoelectric actuators to micromachined silicon structures enables motion from the piezoelectric unimorph to be coupled to tethers. Valve cap strokes as large as 4.8 /spl mu/m were realized for an actuation voltage of 10 V consuming switching energy of 600 nJ. Linear control of fluid flow in the 0-50 /spl mu/l/min was accomplished with pulse width modulated 10 Vpp drive at frequencies as high as 1 kHz.