Patent ID: 8402561

Claim:
An electro-thermal actuator comprising: a plurality of unit cells coupled in parallel, each of the plurality of unit cells comprising a first thermal bimorph, the first thermal bimorph comprising at least two materials having different thermal expansion coefficients bonded together, each of the plurality of unit cells having a first end and second end, wherein the first ends of the plurality of unit cells collectively define a plane, and wherein the second ends of the plurality of unit cells are physically connected at an end point, the plurality of unit cells being operative to move the end point along a first direction that is substantially orthogonal to the plane; a heater that is operative to provide thermal energy to at least one of the plurality of unit cells; a first piezoresistor and a second piezoresistor, the first and second piezoresistors being arranged on the plurality of unit cells such that they are at the substantially the same temperature, wherein each of the first and second piezoresistor cantilevers from the end point such that the free end of the first piezoresistor projects further away from the plane than the free end of the second piezoresistor when the electro-thermal actuator is actuated; and a first temperature sensor that is operative to measure a first temperature at a first location, wherein the first temperature is based on parasitic heat flow through a first unit cell of the plurality of unit cells, and wherein the position of the electro-thermal actuator is based on the temperature at the first location.