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USA: Biotechnology How to Stick Sensors to Skin without Adhesive

Editor: Alexander Stark

Researchers at Binghamton University have discovered how to attach sensors and similar items to human skin without using an adhesive. Their discovery could lead to a patent on a very simple technique that could revolutionize biotech.

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(Source: Binghamton University)

Binghamton/USA — Imagine if you could attach something to your skin without needing glue. A biosensor, a watch, a communications device, a fashion accessory — the possibilities are endless. Thanks to a discovery at Binghamton University’s Thomas J. Watson College of Engineering and Applied Science, that time could be closer than you think. Associate Professor Guy German and Zachary Lipsky, PhD ’21, recently published research in the journal Acta Biomaterialia that explores how human skin can control the way cracks form and why tensometers offer imprecise results when measuring the mechanical properties of biological tissues.


The study that spawned the discovery, titled “The Precision of Macroscale Mechanical Measurements is Limited by the Inherent Structural Heterogeneity of Human Stratum Corneum,” started with German’s roots in mechanical engineering and his interest in testing the validity of Hooke’s law to human skin. “We thought, if we use these standard testing techniques to measure the mechanical properties of tissue, especially skin tissue, is it reporting the right values?” he said. “No one’s really ever validated it.”


“It got me thinking that, in modern times, you can measure how stiff metals and ceramics are. But what about skin?” German said. “Metals or ceramics have a composition that is fairly uniform, but skin and other tissues have a complex and heterogeneous structure with microscale cells connected by cell-cell junctions. The outer layer of skin also exhibits a complex topographical network of microchannels, which are visible if you look at the back of your hand.”


“As the skin expanded, a little crack would grow, and we can measure how much energy it required to grow it by a certain length,” German said. “Typically to measure the energy cost of rupture in mechanical engineering you get two grips, you pull and it splits. You measure the force and displacement and quantify the energy. But this assumes that the material is homogeneous — compositionally the same everywhere. What we found out was that cracks in the skin’s outer layer propagate in a very, very weird way.”


“Because of the heterogeneous structure of skin, it also means that the crack path becomes a lot more random. That’s why you get such variability in macroscale tensometer measurements of skin,” German said, “because even though you get the skin from exactly the same source at exactly the same age, the sample-to-sample variability is so high because the crack paths deviate.”

Reference: The precision of macroscale mechanical measurements is limited by the inherent structural heterogeneity of human stratum corneum; Acta Biomaterialia; DOI:10.1016/j.actbio.2021.05.035