Biomedical engineers have created a very thin skin patch using nanoparticles to record abnormal muscle activity and deliver drugs to patients with movement disorders.
Previous wearable models for drug delivery and monitoring can be relatively bulky and inflexible, but this prototype is built to a much smaller scale that allows secure contact to the skin without sacrificing functionality. Attached to the wrist, the plaster detects muscle tremors then releases drugs into the skin. Researchers say their invention will help patients with movement disorders such as Parkinson's disease or epilepsy. Other variants based on the prototype tested will also detect vital signs such as heart rate and breathing.
The membrane, which looks like a Band-Aid and measures just a millimeter thick, is fabricated using nanoparticles assembled by bottom-up methods onto a tissue-like polymeric substrate. The new fabrication technique allows minute integration of memory, sensor and drug release modules into a tiny, flexible membrane.
"The team use silicon nanomembranes in the motion sensors, gold nanoparticles in the non-volatile memory and silica nanoparticles, loaded with drugs, in a thermal actuator," researchers at startup MC10, wrote in a summary of their findings published in the journal Nature Nanotechnology.
Motion sensors, laid out like waves hundreds of micrometers apart within the plaster, record muscle activity. When the patch is stretched because of movement, filaments record electrical resistance and determine if the movement is an abnormal tremor or just a natural motion of the wrist or arm. The data is recorded in memory cells just 30 nanometers thick. If necessary, heating elements in the patch raise the temperature high enough for nanoparticles to break down and release drugs.
In the future, a wireless communications component like a radiofrequency identification (RFID) module can be integrated into the plaster to allow remote monitoring and control. Smart phones and other devices may also be used as alternatives. A more feasible power source are smart watches, which can have wires that will attach to the plaster to power it or work wirelessly as well.
“Ultimately we will develop a fully automated system that incorporates these sensors and a memory and drug-release mechanism together with a microcontroller to deliver automated drug release in an epidermal patch,” says MC10 co-founder Roozbeh Ghaffari.
On-the-skin drug delivery and monitoring devices have proved a challenge to make because of technical limitations. However, advances in research regarding stretchable electronics and refinement in nanotechnology fabrication techniques have allowed researchers to come up with materials and designs that conquer earlier limitations.
“The system represents a new direction in personalized health care that will eventually enable advanced diagnostics and therapy on devices that can be worn like a child’s temporary tattoo,” says Dae-Hyeong Kim, assistant professor of chemical and biological engineering at Seoul National University, who led the research team.
This development built on earlier research done by John Rogers of the University of Illinois, and founding scientist of MC10, who pioneered work on “epidermal electronics” and the creation of devices worn on the skin to check vital signs. Other researchers have worked on similar studies, such as drug delivery devices implanted under the skin instead of on it, with promising results.
These miniature drug delivery devices and monitoring systems are still prototypes, but their researchers anticipate proceeding with clinical trials and regulatory approval soon. Advances in materials science, nanotechnology and biomedical engineering will have begun to move beyond the research lab into patient rooms.