Compact actuators, electrically programmable microscale surface oxide memory actuators and related robotic devices
Disclosed are devices, systems, and methods for fabrication of moving, actuatable structures at micron scales that can be electronically controlled using low power and low voltages. Also disclosed are microscale robots having such microscale actuator structures to actuate the robots' movements as well as devices, systems, and methods for fabrication of microscale robots. The disclosed methods of fabrication are compatible with standard semiconductor technologies.
1 . An actuator comprising:
a nanoscale-thickness first material; and
a nanoscale-thickness second material disposed along at least a portion of a surface of the nanoscale-thickness first material,
wherein the nanoscale-thickness first material has a first surface stress, the nanoscale-thickness second material has a second surface stress different than the first surface stress, and the actuator is configured to assume a first shape in a first state arising from the difference in the first surface stress and the second surface stress, and wherein the nanoscale-thickness first material is capable of an electrochemically-driven adsorption from an aqueous environment, and the actuator is configured to assume a second shape in a second state arising from ion transfer between the nanoscale-thickness first material and the aqueous environment.
2 . The actuator of claim 1 , wherein the nanoscale-thickness first material includes platinum, ruthenium, rhodium, palladium, osmium, iridium, gold, or silver.
3 . The actuator of claim 2 , wherein the nanoscale-thickness first material is an elongated member, having a first dimension along a first axis, and a second dimension along a second axis perpendicular to the first axis; the first dimension being greater than the second dimension.
4 . The actuator of claim 3 , wherein the nanoscale-thickness second material is inactive of electrochemically-driven adsorption from the aqueous environment.
5 . The actuator of claim 1 , wherein the nanoscale-thickness second material is different from the nanoscale-thickness first material and comprises a graphene, a metal oxide, a metal nitride, titanium, or a noble metal.
6 . The actuator of claim 1 , wherein the nanoscale-thickness first material is platinum or palladium, and the nanoscale-thickness second material is titanium or a noble metal different from the nanoscale-thickness first material.
7 . The actuator of claim 1 , wherein the actuator is configured to assume the second shape in the second state arising from adsorption of hydrogen species, surface oxidation, or adsorption of an oxygen species.
8 . The actuator of claim 7 , wherein the oxygen species comprises at least one of OH − , H 2 O, [H 2 PO 4 ] − , or O 2− .
9 . The actuator of claim 1 , wherein the actuator is configured to assume the second shape in response to application of a voltage across the actuator.
10 . The actuator of claim 1 , wherein the actuator is at least substantially straight in a first state, and wherein the first surface stress and the second surface stress are different.
11 . The actuator of claim 10 , wherein the actuator is configured to assume a curvilinear shape in a second state arising from adsorption of hydrogen species, surface oxidation, or adsorption of an oxygen species.
12 . The actuator of claim 10 , wherein the actuator is configured to assume a curvilinear shape in a second state arising from hydrogen adsorption.
13 . The actuator of claim 10 , wherein the actuator is configured to assume a curvilinear shape in a second state arising from adsorption of an oxygen species.
14 . The actuator of claim 11 , wherein the oxygen species comprises at least one of OH − , H 2 O, [H 2 PO 4 ] − , or O 2− .
15 . The actuator of claim 1 , wherein the nanoscale-thickness first material is between 2 nm and 100 nm thick.
16 . The actuator of claim 1 , wherein the second material is between 0.3 nm and 5 nm thick.
17 . The actuator of claim 1 , wherein the nanoscale-thickness first material is between 6 nm and 8 nm thick.
18 . The actuator of claim 1 , wherein the actuator is a joint actuator of a first member and a second member.
19 . The actuator of claim 9 , wherein the voltage is below about 200 mV or in a range between about 200 mV and about 1.4V.
20 . A nanorobot comprising:
a photovoltaic device; and
the actuator of claim 1 electrically connected to the photovoltaic device.