Researchers Find a Way to Imitate Softness
A team of engineers and psychologists at the University of California San Diego explored the question of the factor that affect how human touch perceives softness for instance, a fingertip against a marshmallow, a rubber ball or clay. They discovered tricks to design materials that imitate different levels of perceived softness.
The findings of the study show fundamental insights into designing tactile materials and haptic interfaces which can recreate real touch sensations. These materials could be applicable for electronic skin, prostheses and medical robotics.
According to Charles Dhong who co-led the study as a postdoctoral fellow at UC San Siego, they are providing a formula to recreate a spectrum of softness and in doing so, they will be helping close the gap in understanding what it takes to recreate aspects of touch. Dhong is currently the assistant professor in biomedical engineering at the University of Delaware. He worked with Darren Lipomi, the study’s co-responding author and a professor of nanoengineering at UC San Diego.
Dhong said that the interesting thing about the study is that they found two new ways to tune the professed softness of an object, micropatterning and changing thickness. Said that Young’s modulus is what scientists usually turn to in terms of what is soft or hard. This is a factor that they could now show that it is only one part of the equation.
The researchers started by examining two parameters engineers use to measure the perceived softness of a material: indentation depth and contact area between the fingertip and the object. Usually, these parameters change simultaneously as a fingertip presses into a material. Touch a piece of soft rubber for instance, and the contact area will increase deeper a fingertip presses in.
Lipomi, Dhong and colleagues got more interested in how indention depth and contact area independently influenced the perception of softness. They specially engineered materials which decoupled the two parameters and then tested them on humans.