A paper-thin, wearable electronic device that monitors a patient’s health status and delivers therapy as required has moved a step closer to reality.
Researchers in South Korea and the US devised a sensor-laden device that can store data, diagnose tremors and deliver a therapy aboard nanoparticles. This has potential for monitoring and treating patients with movement disorders, such as those with Parkinson’s disease.
Remarkable progress has already been made in developing flexible electronics, but scientists have now wrapped arrays of silicon and inorganic solid-state sensors, resistive heaters, non-volatile memory devices and a drug release mechanism into one device. The results are reported in Nature Nanotechnology (DOI: 10.1038/NNANO.2014.38).
“We took a class of soft, stretchable electronics and used it in a new way to detect tremor responses. We set up a platform then to deliver active ingredients to the skin, so devising a fully integrated system that is both diagnostic and therapy,” explained Roozbeh Ghaffari, a co-author of the report and co-founder and Director of Technology at MC10 Inc.
By increasing the temperature in the device, nanoparticles were shown to diffuse into the epidermis. “We did that in a controlled way on in vitro skin models, using pig skin, showing that we can have actuators such as thermal actuators so you can heat up the patch,” Ghaffari told in-PharmaTechnologist. Light or electrical triggers could also be used.
Senior author Dae-Hyeong Kim at Seoul National University in Korea added: “If the patient’s condition is serious, we can increase the temperature by turning on the embedded heater. Then the drug delivery speed can be increased. After the faster drug delivery, the patient gets better, and the temperature can be decreased by turning down the heater. Then the drug delivery speed will be slowed down. “
Ghaffari explained that the idea is to have a thin layer of drug on an adhesive layer at the bottom of the electronic patch that could be taken off once it has been depleted. Right above that therapeutic adhesive layer would be the thermal heater that triggers drug release. The “smarts” of the device are its diagnostic capabilities – in this case its ability to measure tremors.
“This could be a completely automated system for say Parkinson’s disease patients, so that when you undergo a tremor or seizure, the release state is activated and the system automatically delivers the correct amount of the drug,” said Ghaffari.
The device described in the paper had a memory array transfer-printed on the bottom side of an elastomeric skin patch. The electroresistive heater/temperature sensor was fabricated on the top-side of the patch, with a silicon strain sensor on the opposite side. The wearable system is the thickness of paper and around the size of three postage stamps.
A more reliable and cheaper system is now required for practical applications, said Dae-Hyeong Kim. Parkinson’s disease is a condition for which there is already a drug on the market delivered across the skin.