Stretchy hydrogel based multi-purpose ‘Band-Aid' with sensors
- December 27, 2015
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The inventions in the field of medicine and electronics are growing at an unimaginable rate. When the powerful capability & functionality of electronics is applied in the medicine field the end result is mind blowing & life saving. Few engineers from MIT have designed a multi-purpose Band-Aid which is made of a gel-like material. It comprises of miniature temperature sensors and LEDs with other electronic components as well as tiny, drug-delivering reservoirs and channels. The 'smart wound dressing' releases medicine in response to changes in skin temperature and can be designed to light up if, say, medicine is running low.
Xuanhe Zhao, the Robert N. Noyce Career Development Associate Professor in MIT's Department of Mechanical Engineering designed the Hydrogel matrix. It is a rubbery material, mostly composed of water, designed to bond strongly to surfaces such as gold , titanium, aluminium, silicon, glass, and ceramic. It is bonded to a matrix of polymer islands which incorporates the different components required. When the dressing is applied to a highly flexible area, such as the elbow or knee, it stretches with the body, keeping the embedded electronics functional and intact.
The electronics coated in hydrogel may be used not just on the surface of the skin but also inside the body, for example as implanted, biocompatible glucose sensors, or even soft, compliant neural probes. The stretchable and sticky nature of the material is highly essential in order for it to function as a band-aid. Zhao says” The human body and electronics have totally different properties; Electronics are usually hard and dry, but the human body is soft and wet. It is highly desirable to make the electronic devices soft and stretchable to fit the environment of the human body. That's the motivation for stretchable hydrogel electronics."
Synthetic hydrogels are often used as degradable biomaterials at the current stage due to their weak properties. If we want to make an electronic device out of hydrogels, we need to think of long-term stability of the hydrogels and interfaces.
So his team came up with a design strategy for robust hydrogels, mixing water with a small amount of selected biopolymers to create soft, stretchy materials with a stiffness of 10 to 100 kilopascals -- about the range of human soft tissues. The researchers also devised a method to strongly bond the hydrogel to various nonporous surfaces.
They also tried encapsulating a titanium wire to form a transparent, stretchable conductor. In experiments, they stretched the encapsulated wire multiple times and found it maintained constant electrical conductivity.
The researchers also created pathways for drugs to flow through the hydrogel, by either inserting patterned tubes or drilling tiny holes through the matrix. They placed the dressing over various regions of the body and found that even when highly stretched the dressing continued to monitor skin temperature and release specific drugs from the required reservoir according to the sensor readings.
Yuk says an immediate application of the technology may be as a stretchable, on-demand treatment for burns or other skin conditions.
By further studies Zhao envisions hydrogel to be an ideal, biocompatible vehicle for delivering electronics inside the body. He is currently exploring hydrogel's potential as a carrier for glucose sensors as well as neural probes. Conventional glucose sensors, implanted in the body, typically spark a foreign-body response from the immune system, which covers the sensors with dense fibers, requiring the sensors to be replaced often. While various hydrogels have been used to coat glucose sensors and prevent such a reaction, the hydrogels are brittle and can detach easily with motion. Zhao says the hydrogel-sensor system his group is developing would likely be robust and effective over long periods. He says a similar case might be made for neural probes.
It is really tough can quantify the scale at which technology is growing nowadays. Stretchable hydrogel electronics and devices seem to produce The Band-Aid of the future. The pros and cons of it can be analysed when it comes to large scale production and usage. But as of now it is an ingenious & fruitful invention in the field of electronics.
Shaoting Lin, Hyunwoo Yuk, Teng Zhang, German Alberto Parada, Hyunwoo Koo, Cunjiang Yu and Xuanhe Zhao. Stretchable Hydrogel Electronics and Devices. Advanced Materials, December 2015 DOI: 10.1002/adma.201504152