Pressure and strain sensors that can be bent 4,000 times without loss of performance.
More than 10 times more sensitive than existing sensors, good elasticity, and chemical stability

A Korean research team has successfully developed a rubber-type pressure sensor that can be directly attached to prosthetic limbs, prosthetic arms, and robots for people with disabilities. This suggests that future use of this sensor could mimic the function of the human nervous system, aiding in sensory perception.

Following the development of a fabric-type sensor based on graphene composites earlier this year, the Electronics and Telecommunications Research Institute (ETRI) has now developed a rubber-type sensor. This has resulted in the development of a rubber-type pressure and strain composite sensor that boasts high reproducibility even after thousands of bends and stretches and offers sensitivity more than 10 times higher than existing sensors.

The researchers created a 1cm x 1cm sensor for testing purposes. The sensor size can be adjusted in the future. Initially, they plan to develop a small sensor that can be applied to gloves or fingers, maximizing sensitivity to even the smallest pressure.

ETRI stated that although existing pressure sensors can secure sensitivity, their response to pressure changes is low, and that they have worked hard to solve this problem.

The researchers also used a resistive sensor method in which resistance changes as area or length changes. This is because changes in resistance make it easy to check whether the sensor is operating.

In particular, we tried to find a material that was not hard or uncomfortable to the skin, especially for application to human skin. So, he explained that he chose a rubber-like material called Ecoflex, which is elastic and harmless to the human body.

The research team explained that 3D graphene resembles a sponge, and when pressed and released with a hand, the resistance changes as the length or area changes. Because the sponge's surface is coated with graphene and thus conductive, applying vertical pressure allows for changes in resistance according to changes in surface area.

Afterwards, they revealed that they were able to create a flexible rubber-type sensor with high sensitivity by making a relief flat sheet using molybdenum disulfide (MoS2) on the surface of a graphene sponge and then combining it with Ecoflex, a flexible polymer. This resulted in the creation of a sensor that exhibited excellent electrical conductivity and high sensitivity even to low pressure changes.

The research team predicts that this type of rubber sensor will be first applied to prosthetic limbs and robots in the future, and will also be of great help in rehabilitation treatment in hospitals.

Especially in the case of rehabilitation treatment, it was very difficult to know the degree of recovery during the treatment process, but it is explained that if this sensor is attached to the patient and used, accurate quantitative analysis of the degree of treatment is possible.

In other words, if a sensor is attached to the skin during the rehabilitation process of the patient raising his or her arm, it is possible to easily observe the change in resistance according to the arm lifting.

Testing a human-safe, electronic skin-type tactile sensor.