Wearable hydrogel to deliver drugs onto skin or inside the body

Massachusetts Institute of Technology (MIT) engineers have designed a sticky, stretchy, hydrogel that can incorporate temperature sensors, electronics and 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 medicine is running low.

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 key to the design is a rubbery hydrogel matrix designed by Xuanhe Zhao, professor in MIT’s department of mechanical engineering.

Zhao and 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 devised a method to strongly bond the hydrogel to various nonporous surfaces such as gold, titanium, aluminum, silicon, glass and ceramic.

In a new paper published in the journal Advanced Materials, the MIT team reports embedding various electronics within the hydrogel to create a “smart wound dressing,” comprising regularly spaced temperature sensors and tiny drug reservoirs.

The MIT 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 drugs according to the sensor readings.

Zhao’s co-authors on the paper were graduate students Shaoting Lin, Hyunwoo Yuk, German Alberto Parada, postdoc Teng Zhang, Hyunwoo Koo from Samsung Display and Cunjiang Yu from the University of Houston. 

Yuk said an immediate application of the technology may be as a stretchable, on-demand treatment for burns or other skin conditions.

Yuk said: “The unique capability here is, when a sensor senses something different, like an abnormal increase in temperature, the device can on demand release drugs to that specific location and select a specific drug from one of the reservoirs, which can diffuse in the hydrogel matrix for sustained release over time.”

Zhao said electronics coated in hydrogel may also 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.