Saturday, September 24, 2022

An ultrathin pressure sensor to measure a sense of touch

World’s first fingertip-mounted sensor that maintains the user’s sensitivity.

The “sense of touch” is what gives our brains a wealth of information about the natural environment, including temperature, humidity, and air pressure. Most importantly, this sense of touch lets us feel physical pain–a necessity for avoiding injury, disease, and danger.

It is truly unique how much information we receive about the world through our sense of touch, and although we still don’t know all about how the sense of touch works. Discovering it would be beneficial not only for research in medicine, sports, or neuroengineering but also for archiving skills.

David Franklin, Professor for Neuromuscular Diagnostics at TUM, and his colleagues teamed up with scientists from the University of Tokyo to develop a sensor attached directly to the skin. Dubbed as a ‘nanomesh sensor,’ the sensor can measure how fingers interact with objects to produce valuable data for technological or medical applications.

The sensor is covered by four ultrathin layers of functional and porous materials: A layer of polyurethane nanofibers serves as a passivation and carrier layer, an ultra-thin layer of gold mesh, an intermediate layer of parylene-coated polyurethane nanofibers, and finally, another layer of a gold mesh.

The effect of the sensor on human sensation was quantitatively investigated on 18 participants. All of them confirmed that the sensors were imperceptible and affected neither the ability to grip objects through friction nor the perceived sensitivity than performing the same task without a sensor attached.

Franklin said“In the past, we only had relatively rigid measuring instruments that interfere with the sense of touch. Think about your pet at home, perhaps your cat or dog. Which instrument is both soft and sensitive enough to measure how much pressure you use when caressing it? Until now this was impossible, but with this new nanomesh sensor applied on our fingers we suddenly can.”

“By applying the ultrathin nanomesh sensor on the fingertips, we could measure the force and record it without influencing the finger’s sense of touch.”

“This is the first time in the world that a fingertip-mounted sensor with no effect on skin sensitivity has been successfully demonstrated. And the sensor maintained its performance as a pressure sensor even after being rubbed against a surface with a force equivalent to atmospheric pressure, 300 times without breaking.”

“This shows that we can measure the manipulation of a huge range of objects – this has never been possible before.”

Journal Reference:
  1. Sunghoon Lee, Sae Franklin, Faezeh Arab Hassani, Tomoyuki Yokota, Md Osman Goni Nayeem, Yan Wang, Raz Leib, Gordon Cheng, David W. Franklin, Takao Someya: Nanomesh pressure sensor for monitoring finger manipulation without sensory interference. Science, DOI: 10.1126/science.abc9735

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