‘Band-aid’-like invention delivers medicine to the skin

Engineers from the Massachusetts Institute of Technology have invented what may be called the band-
aid of the future.

They designed a stretchy hydrogel that is able to include temperature sensors, LED
lights, as well as other electronic devices, such as tiny reservoirs and channels that are able to release
drugs.

If this material is applied to a highly flexible area, or an area that frequently moves in the body, such as
the elbow or knee, it adapts by stretching, thereby protecting the incorporated electronics and keeping
them functional.

The star of this invention is the hydrogel matrix that was designed by Xuanhe Zhao who is the Robert N.
Noyce Career Development Associate Professor in the Department of Mechanical Engineering in MIT. The
hydrogel is designed to bond strongly to materials such as gold, titanium, silicon, aluminum, ceramic and
glass.

Zhao and colleagues published their paper in the journal Advanced Materials, and they embedded various
electronic materials in the hydrogel. The electronics that are on the surface of the hydrogel can actually
be used not only on the skin, but inside the body as well.

Skin Hydrogel

The problem usually is that because the human body is soft and wet, electronics, which are hard and dry,
are not quite compatible for use. If you want to put electronics in close contact with the human body for
applications such as health care monitoring and drug delivery, 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, says Zhao.

At present, hydrogels are used as degradable biomaterials, as they are usually brittle, barely stretchable
and adhere weakly to most surfaces. In order to make electronic devices out of this material, factors such
as the long-term stability of the hydrogel and interfaces have to be considered. In order to deal with these
obstacles, Zhao's team thought up of a strategy that involves mixing water with a small amount of special
biopolymers that would enable them to create soft and stretchy materials with the stiffness that as akin
to that of human soft tissues. They were also able to think of a strategy that allowed the hydrogel to bond
strongly with a variety of non-porous substances.

Because of this, they were able to embed various materials, allowing for the hydrogel to have many uses.
They used the hydrogel as an encapsulation for a titanium wire, forming a transparent and stretchable
conductor. The researchers also embedded LED lights in the hydrogel, forming an array, and when
attached to various parts of the body, the lights still continued working. Finally, the group combined many
electronic devices, such as regularly spaced temperature sensors and tiny drug reservoirs, within the
hydrogel to create the smart wound dressing. They placed the dressing on different parts of the body
and even when highly stretched, it still continued to function.

Hyunwoo Yuk, a member of the team, says that the invention may be used for example as a treatment
method for burns or other skin conditions. They envision that the hydrogel would prove very useful
especially as a biocompatible vehicle for delivering electronics inside the body.

To know more about skin treatments, feel free to read our other articles on this site.