Towards self-sensing soft robots with electrochemically driven pumps
Researchers design a transducer powered by electrochemical reactions for operating fluid pumps without cumbersome parts in soft robots

Date:
February 8, 2022
Source:
Shibaura Institute of Technology
Summary:
Soft robots have received much attention recently due to their
adaptability and safety. However, the fluidic systems used in these
robots continue to use pumps that are large, heavy, and noisy. Now,
researchers report a fluid pump driven by electrochemical reactions
that are simple, lightweight, silent, and enable self-sensing
actuation, with potential applications in wearable technology and
touch display devices.



FULL STORY ==========================================================================
The word "robot" would probably conjure up images of hard metallic bodies
that are invulnerable to attacks. In modern day-to-day life, however,
robots are hardly needed for defending against enemy attacks. Instead,
they are required to perform more mundane tasks such as handling delicate objects and interacting with humans. Unfortunately, conventional robots
perform poorly at such seemingly simple tasks. Moreover, they're heavy
and often noisy.


==========================================================================
This is where "soft" robots have the upper hand. Made of materials called "elastomers" (materials with high viscosity and elasticity), soft robots
absorb shocks better, can adapt better to their environments, and are
safer compared to conventional robots. This has allowed for a broad
range of applications, including medicine and surgery, manipulation,
and wearable technology. However, many of these soft robots rely on
fluidic systems, which still use pumps operated by mechanical parts
(motors and bearings). As a result, they are still heavy and noisy.

One way around this problem is to use chemical reactions to drive
pumps. But while such systems are definitely lightweight and quiet,
they don't perform as well as conventional pumps. Is there a way to beat
this trade-off? Turns out, the answer is yes. A team of researchers from Shibaura Institute of Technology (SIT), Japan, led by Prof. Shingo Maeda, introduced an "electrohydrodynamic" (EHD) pump that uses electrochemical reactions to drive pumps. The EHD pumps have all the advantages of pumps
driven by chemical reactions and none of their issues.

Now, 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 one step further, designing a "self-sensing" EHD pump that uses an electrochemical dual transducer
(ECDT) to sense the fluid flow, which, in turn, activates electrochemical reactions and increases 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," explains Prof. Maeda. This paper was made available online
on 7 January 2022 and was published in Volume 14 Issue 2 of the journal
ACS Applied Materials & Interfaces on 19 January 2022.

The team based the ECDT design on the EHD pump they had previously
designed.

The pump consisted of a symmetrical arrangement of planar electrodes,
which allowed an easy control of the flow direction by simply changing
the voltage.

Moreover, the arrangement enabled an obstruction-free flow and in the
same amount in each direction owing to same strength of the electric
field on either side.

The team evaluated sensing performance in terms of range of detectable
flow, rate, sensitivity, response, and relaxation times, and also used mathematical modeling to understand the sensing mechanism. "The ECDT
can easily be integrated into a fluidic system without bloating or
complexity," says Yu Kuwajima, doctoral student at the Smart Materials Laboratory (SIT) and the first author of the study. Additionally, the researchers tested its performance by using it to drive a suction cup
to detect, 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,"
says Prof. Maeda.

However, the ECDT is more than just about soft robot
miniaturization. It is a step towards a future in which humans
and robots would not simply co-exist but their interaction would
become fluid and natural. An exciting prospect to entertain, for sure! ========================================================================== Story Source: Materials provided by
Shibaura_Institute_of_Technology. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Yu Kuwajima, Yumeta Seki, Yuhei Yamada, Satoshi Awaki, Shota
Kamiyauchi,
Ardi Wiranata, Yuto Okuno, Hiroki Shigemune, Shingo Maeda.

Electrochemical Dual Transducer for Fluidic Self-Sensing
Actuation. ACS Applied Materials & Interfaces, 2022; 14 (2):
3496 DOI: 10.1021/ acsami.1c21076 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220208085019.htm
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