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Innovative Ink Allows to Print Flexible, Stretchable and Multi-Layer Circuits

This technology can be widely applied in health monitoring, to produce artificial skin, flexible solar panels, LCDs, or wearable devices

A recent article from the “Soft and Printed Microelectronic” Laboratory (SPM-UC) at Universidade de Coimbra, led by Mahmoud Tavakoli – a CMU Portugal Faculty member and WOW PI – was selected as the Cover Page of the ACS Applied Materials and Interfaces Journal. This research work introduces a unique printable ink that allowed, for the first time, digital printing of multi-layer stretchable circuits, e-skins and adhesive medical patches for electrophysiological monitoring. The ink formulation is patented jointly by the University of Coimbra and Carnegie Mellon University.

This paper introduces the first report on materials and methods that allow scalable fabrication of stretchable circuits, using simple extrusion printers. These electrical circuits can be printed on a medical adhesive, for patient biomonitoring, over an elastic polymer to make  artificial skin for robotics application or even to be printed over the textile for wearable computing.

Mahmoud Tavakoli explains that “to integrate electronics into textile for wearables or on polymers for biomonitoring patches, it is necessary that these electronics are stretchable, and elastic. In the last decade, many researchers have worked on stretchable electronics. However, it has been difficult to produce these circuits in a scalable fashion”. But now, with this new invention “these circuits can be easily printed using low-cost printers. This work presents an enabling technology, that will allow companies to produce billions of these patches quickly and cost-effectively. As everything is performed at the room temperature, the ink is compatible with heat resistant substrates, such as medical adhesives for wound dressing and this is something that is being used now in the WoW project for making on-skin patches.”

The research presented under this article is being partially funded by the Large Scale project WoW of the CMU Portugal Program headed at Universidade de Coimbra by Mahmoud Tavakoli, in a consortium led by the company GLINTT in collaboration with ISR Institute from Universidade de Coimbra, Centro Hospitalar e Universitário de Coimbra and the Department of Mechanical Engineering at CMU.

The study also demonstrates that this new ink has a high conductivity and extreme extensibility, allowing to print ultrathin circuits, with several layers and highly flexible. “Unlike other substances such as ordinary metal liquids, this ink is easy to print, does not stain and is easily applied to a wide variety of materials. Additionally, it is now possible to print elastic circuits with a simple extrusion printer, which makes it accessible for universities and industries to make their devices rapidly, and is a significant step toward scalable fabrication at a reduced cost”, adds the researcher. In fact, the cost reduction and scalability will enable the application of this technology to other fields of research and other uses such as stretchable batteries, stretchable super capacitors, flexible displays, and solar panels.

Currently the research team is showcasing different applications of this enabling technology, and at the same time they are working with the technology transfer offices at the University of Coimbra (UC Business), for licensing the technology for different applications, such as health, printed electronics, and e-textile.

CMU version of this News in the Mechanical Engineering website.

More about the WoW Project

Electronic skin (e-skin) patches with biomonitoring sensors that adhere to the human epidermis are highly transformative in patient monitoring. These devices can collect and classify physiological and behavioral data, including heart, muscle, brain activities, respiration rate, body temperature, and blood oxygen.  WoW proposes a novel architecture focused on untethered, simple, and low-cost printed biomonitoring stickers, not only to be used in patients but also in patients’ beds, that are equipped with a smart IoT unit. The bed-sticker connection allows for data acquisition and transmission and enables energy transmission to the stickers.

Link to the article here.
Link to the Cover page here.