A 3D-printed robotic finger from thermo-reactive materials inspired by nature

Bioinspired robo-finger feels like the real thing

American researchers have created a 3D printed bioinspired robotic finger that looks and moves almost like a real human finger. 

Made of shape memory alloy, the finger contains two types of actuators that provide its ability to flex and extend. The two actuators react to heat. While the extensor actuator takes a straight shape when heated, the flexor becomes curved. This way, the robotic finger mimics the natural motion of human fingers.

"We have been able to thermomechanically train our robotic finger to mimic the motions of a human finger like flexion and extension," said Erik Engeberg, assistant professor in the Department of Ocean and Mechanical Engineering at Florida Atlantic University. "Because of its light weight, dexterity and strength, our robotic design offers tremendous advantages over traditional mechanisms, and could ultimately be adapted for use as a prosthetic device, such as on a prosthetic hand."

The device, described in the latest issue of the journal Bioinspiration & Biomimetics, will be first used in undersea applications in depths, which are too risky for humans to operate in.

To create the finger, the researchers first 3D printed the inner and outer mould that houses the flexor and extensor actuator and a position sensor. Subsequently, the researchers used plates of shape memory alloy (SMA) to create the individual parts of the finger. An electrical chassis was inserted into the structure to allow electric currents to flow through each actuator to drive its motion.

The major drawback of the system is the relatively long time required for the finger to change from the extended to the flexed state.

"Because SMAs require a heating process and cooling process, there are challenges with this technology such as the lengthy amount of time it takes for them to cool and return to their natural shape, even with forced air convection," said Engeberg. "To overcome this challenge, we explored the idea of using this technology for underwater robotics, because it would naturally provide a rapidly cooling environment."

The researchers said the technology worked better in the undersea environment than other similar technologies.

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