Scientists from the Technical University of Munich (TUM) and the University of Tokyo have developed an ultrathin pressure sensor that can be attached directly to the skin. It can measure how fingers interact with objects to produce valuable data for technological or medical applications. The sensor has an unnoticeable effect on the users’ sensitivity and ability to grip objects, and it is highly resistant to disruption from rubbing.
Our hands and fingers are our primary tools for direct interaction with materials, other human beings and our immediate environment. Finding out how the sense of touch actually works and having ways to record it would be a great benefit not only for research in the fields of medicine, sports or neuroengineering, but also for archiving skills.
However, capturing this data is not easy. A wearable sensor on a finger has to be extremely thin and flexible, because fingertips are so sensitive that anything could affect the feeling. In addition, a sensor worn on hands needs to be resistant to rubbing or other physical damage.
To overcome this problem, David Franklin, Professor for Neuromuscular Diagnostics at TUM and his colleagues teamed up with researchers from the University of Tokyo. Here, a group of scientists led by TUM-IAS Alumnus Hans Fischer Senior Fellow Professor Takao Someya had developed a sensor covered by four ultrathin layers of a functional and porous material named “nanomesh sensor”.
Thinner than a human hair
A layer of polyurethane nanofibers serves as a passivation and carrier layer. This is followed by an ultra-thin layer of gold mesh, an intermediate layer of parylene-coated polyurethane nanofibers and finally another layer of gold mesh. A thin top-layer of polyurethane and polyvinyl alcohol nanofibers mechanically protects the four layers of the sensor.
“Both nanomesh layers were made by a process called electro spinning,” Someya says. The polyurethane fibers are between 200 to 400 nanometers thick, about two hundreds the thickness of a human hair.
The other two layers are a stencil-like network of lines that form the functional electronic component of the sensor. They are made from gold and use a supporting frame of polyvinyl alcohol, a polymer which is also used for contact lenses. After the manufacturing process, the polymer is washed away to leave only the gold traces it was supporting.
The full press release can be found here.
Relevant publication:
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