Development of an Electrothermal Actuator

This type of actuator was a prototype as a replacement to the Pneumatic Network Actuator without using pressurized air.

Here, for two different iterations, ethyl Alcohol and Acetone were respectively added to each specimen to form 20% of the PDMS pre-cured solution and then cast to form the same design as the PNA, With a Nichrome wire embedded in the chamber as a heating element.

The phenomenon occurring here is that when the electricity is passed through the Nichrome wire, the droplets of Acetone/Ethyl Alcohol trapped inside PDMS is evaporated and expansion of that part of the material is produced.

Here in case of Acetone based actuator, the acetone got evaporated very rapidly and fumes cannot be trapped inside PDMS thus re-actuation was not possible. But with the Ethyl alcohol-based actuator, the alcohol remained inside the material and the actuator could be reheated for reuse of the actuator.

However, the time cycle of actuation of this actuator took 3-4 minutes, which is a lot of time. Also, the cooling of the actuator took a lot of time because there was no other medium except air-cooling. Hence, this type of actuator was discarded as it lacks more research and time to be invested in it.

                                                                           Figure 1  a) Electrothermal Actuators             b) Mold and nichrome wire 

                                                                          Figure 2a)ETA After Actuation                                 b)ETA Before actuation