**2. Thermal microactuator designs**

Figure 1 shows schematics of three thermal microactuator designs: bimaterial, bent-beam, and flexure. Bimaterial actuators consist of materials with different coefficients of thermal expansion and function similarly to a bimetallic thermostat (Ataka et al., 1993). When the temperature changes due to an embedded heater, the microactuator moves due to the difference in the expansion associated with the temperature change (Fig. 1a). Bent-beam

Fig. 1. Schematics of thermal microactuators: a) bimaterial, b) bent-beam, and c) flexure

Fig. 2. Microscope pictures of thermal microactuators: a) electrically powered bent-beam, b) electrically powered flexure, c) laser powered bent-beam, and d) laser powered flexure

Figure 1 shows schematics of three thermal microactuator designs: bimaterial, bent-beam, and flexure. Bimaterial actuators consist of materials with different coefficients of thermal expansion and function similarly to a bimetallic thermostat (Ataka et al., 1993). When the temperature changes due to an embedded heater, the microactuator moves due to the difference in the expansion associated with the temperature change (Fig. 1a). Bent-beam

Fig. 1. Schematics of thermal microactuators: a) bimaterial, b) bent-beam, and c) flexure

Fig. 2. Microscope pictures of thermal microactuators: a) electrically powered bent-beam, b) electrically powered flexure, c) laser powered bent-beam, and d) laser powered flexure

b)

**2. Thermal microactuator designs** 

a) b)

c) d)

c)

a)

actuators have angled legs that expand when heated, providing force and displacement output as shown in Fig. 1b (Park et al., 2001; Que et al., 2001). The flexure actuator in Fig. 1c contains asymmetric legs, for example of unequal width, that flex to the side due to differential expansion when heated (Comtois et al., 1998). Figure 2 has pictures of electrically and optically powered bent-beam and flexure thermal microactuators.
