The term “robot” would probably summon up images of sturdy metallic bodies that are indestructible when attacked.
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In modern routine life, however, robots are barely needed for guarding against enemy attacks. Instead, they are needed to carry out more ordinary errands such as interacting with humans and handling delicate objects.
Regrettably, conventional robots do not perform well at such apparently basic tasks. Furthermore, they are heavy and quite noisy.
As “soft” robots are composed of materials known as “elastomers” (materials possessing high viscosity and elasticity), they tend to have the upper hand.
Soft robots can absorb shocks and adapt to their environments in a better manner and are safer than conventional robots. This has facilitated a broad range of applications, including manipulation, medicine and surgery, and wearable technology.
However, a number of these soft robots depend on fluidic systems, which still use pumps worked by mechanical components (bearings and motors). Therefore, they are still noisy and heavy.
One way to overcome this issue is to use chemical reactions to power pumps. But while such systems are certainly lightweight and quiet, they do not do as well as conventional pumps. Is there a technique to beat this trade-off? There is a solution.
A team of scientists from Shibaura Institute of Technology (SIT), Japan, directed by Prof. Shingo Maeda, launched an “electrohydrodynamic” (EHD) pump that employs electrochemical reactions to power pumps. The EHD pumps have all the benefits of pumps powered by chemical reactions minus their issues.
Currently, in a recent study, the team, including Prof. Maeda, Yu Kawajima, Dr. Yuhei Yamada (all from the Department of Engineering Science and Mechanics, SIT), and Associate Professor Hiroki Shigemune (Department of Electrical Engineering, SIT) has gone a step further, engineering a “self-sensing” EHD pump that uses an electrochemical dual transducer (ECDT) to detect the fluid flow, which, in turn, triggers electrochemical reactions and boosts current.
Self-sensing technology has attracted much attention recently for compactifying soft robots. Incorporating sensors in soft robots enhances their multifunctionality, but often make for complex wiring and bloating. Self-sensing actuation technology can help solve this issue and allow for miniaturization of soft robots.
Prof. Shingo Maeda, Study Lead, Department of Engineering Science and Mechanics, Shibaura Institute of Technology
This study has been published in Volume 14 Issue 2 of the journal ACS Applied Materials & Interfaces on January 19th, 2022.
The researchers based the ECDT design on the EHD pump they had developed earlier. The pump comprised a symmetrical positioning of planar electrodes, which allowed easy control of the flow direction by just altering the voltage.
Additionally, the positioning allowed a barrier-free flow and in the same amount in each direction because of the same strength of the electric field on either side.
The researchers assessed the sensing performance with regard to a range of detectable flow, rate, response, sensitivity, and relaxation times, and also employed mathematical modeling to comprehend the sensing mechanism.
The ECDT can easily be integrated into a fluidic system without bloating or complexity.
Yu Kuwajima, Study First Author and Doctoral Student, Smart Materials Laboratory, Shibaura Institute of Technology
Furthermore, the team verified its performance by using it to power a suction cup to sense, grab, and release objects.
The advantages of the ECDT are that it does not require any special equipment or complex processing for its fabrication. Moreover, it is small, lightweight, and demonstrates a wide range of sensitivity.
Prof. Shingo Maeda, Study Lead, Department of Engineering Science and Mechanics, Shibaura Institute of Technology
However, the ECDT is beyond just soft robot miniaturization. It is a path toward a future in which robots and humans would not merely co-exist but their contact would turn out to be fluid and natural. An exhilarating prospect in the years ahead.
Journal Reference:
Kuwajima, Y., et al. (2022) Electrochemical Dual Transducer for Fluidic Self-Sensing Actuation. ACS Applied Materials & Interfaces. doi.org/10.1021/acsami.1c21076.