A 3D-Printed Hydrogel That Can Walk Underwater & Move Objects

  • New 3D printed smart gels can walk underwater, pick objects and move them. 
  • Their movements and shape can be controlled by applying varying electric fields. 
  • It could lead to the development of artificial stomach, heart, and other muscles. 

Different types of soft robots and actuators use shape memory polymers and hydrogels that are triggered by external stimuli like pH, temperature or electric field. Specifically, electroactive hydrogels are attracting a lot of attention these days due to their unique features such as ease of control, fast actuation, and biomimetic material properties.

So far, the design of these electroactive hydrogels has been limited to 2D fabrication techniques like molding and lithography. Also, most of their actuations have remained simple.

Recently, researchers at Rutgers University demonstrated a simple locomotion of an electroactive hydrogel structure. It can walk underwater, pick objects and move them. Compared to hard devices, it’s simple to design, control, and cheaper to manufacture.

How Did They Come Up With This Smart Gel?

In this study, researchers demonstrated soft robotic locomotion and manipulation of the three-dimensional hydrogel using projection micro-stereolithography – a quick and flexible digital light processing technology.

A light-sensitive solution is exposed to light during the printing process. This solution becomes gel, which is further placed in a solution of salty water. Then two thin wires apply varying electric currents to stimulate different motions. The gel looks like a walking human and is nearly one inch tall.

Hydrogel walks underwater | credit: Rutgers University 

In order to better understand and manipulate actuation, they analyzed hydrogel’s bending deformation for several electrolyte concentrations and electric field strength They also examined the effects of hydrogel’s structure and its thickness, with the help of projection micro-stereolithography technique.

The team discovered that the 3D printed gel shows the highest deformation in an electrolyte with a particular ionic strength (in this case, with 0.05 M PBS [Phosphate Buffered Saline] solution), and deformation directly depends on the strength of the applied electric field. Also, the actuation time scale changes linearly with gel’s thickness.

Reference: ACS Publications | doi:10.1021/acsami.8b04250 | Rutgers University

In simple language, the speed of movement of hydrogel can be controlled by altering its dimension (thicker gel moves slower). Since the hydrogel is made up of soft material, has over 70% of water and triggers on electrical stimulation, it resembles contracting muscles.

Utilizing these key points, they demonstrated 2 actuators, 1 gripper and 1 object transporter, printed with actuation components. The bi-directional locomotion of hydrogel was achieved through deformation-induced shift of the center of gravity in an electric field.

How It’s Useful?

The research shows that how modern 3D printing methods could enhance the size, design, and versatility of hydrogel material. In this case, scientists were able to build smart gel featuring unprecedented motions.

The watery creation can lead to soft robots mimicking sea animals that can crawl/walk underwater and bump into objects without harming them. Furthermore, gels that remain solid despite their 70% water content, are found in Jell-O, contact lenses and even in the human body.

Read: New Smart Bandage Can Monitor And Deliver Drugs To Improve Healing

Therefore, along with conducting underwater investigations, this smart gel could help in the development of artificial stomach, heart and other muscle, as well as instruments for detecting, diagnosing diseases and delivering drugs.

Written by
Varun Kumar

Varun Kumar is an experienced science and technology journalist interested in machines, AI, and space exploration. He received a Master's degree in computer science from Indraprastha University. To find out what his latest project is, feel free to directly email him at [email protected] 

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