HASEL actuators synergize the strengths of soft fluidic and soft electrostatic actuators, (Credit: University of Colorado – Boulder)

Researchers have developed a new class of soft, electrically activated devices capable of mimicking the expansion and contraction of natural muscles. These devices, which can be constructed from a wide range of low-cost materials, are able to self-sense their movements and self-heal from electrical damage, representing a major advance in soft robotics.

The soft devices can perform a variety of tasks, including grasping delicate objects, such as a raspberry and a raw egg, as well as lifting heavy objects.

The newly developed hydraulically amplified self-healing electrostatic (HASEL) actuators eschew the bulky, rigid pistons and motors of conventional robots for soft structures that exceed or match the strength, speed, and efficiency of biological muscle. Their versatility may enable artificial muscles for human-like robots and a next generation of prosthetic limbs.

One iteration of a HASEL device consists of a donut-shaped elastomer shell filled with an electrically insulating liquid (such as canola oil) and hooked up to a pair of opposing electrodes. When voltage is applied, the liquid is displaced and drives shape change of the soft shell. As an example of one possible application, the researchers positioned several of these actuators opposite of one another and achieved a gripping effect upon electrical activation. When voltage is turned off, the grip releases.