ELECTRONIC TATTOOS FOR WEARABLE COMPUTING
University of Coimbra, teamed up to develop methods for direct printing of stretchable electronic circuits. Their collaboration succeeded. “The technique is simple. The tattoos are ultrathin, very stretchable, and inexpensive to produce,” said Majidi. “This is a breakthrough in the printed electronics area,” said Tavakoli. “We showed for the first time that inkjetprinted patterns of silver nano particles can be sintered at room temperature using the gallium indium alloy. Removing the need for high temperature sintering makes
Researchers from Carnegie Mellon University’s College
our technique compatible with thin-film and heat sensitive
of Engineering and the Institute of Systems and Robotics
substrates.” In addition to low-cost processing, these tattoos provide
simple, efficient method to make robust, highly flexible,
other advantages. Because they have mechanical properties
tattoo-like circuits for use in wearable computing. The
similar to lightweight fabrics, they remain functional under
low-cost process adds trace amounts of an electrically
bending, folding, twisting, and strains above 30% (which is
conductive, liquid metal alloy to tattoo paper that adheres
the typical stretchability of human skin). They can conform
to human skin. These ultrathin tattoos can be applied
and adhere to highly curved 3D surfaces, like a model of a
easily with water, the same way one would apply a child’s
human brain or a lemon.
decorative tattoo with a damp sponge. Other tattoo-like electronics either require complex fabrication techniques inside a cleanroom or lack the material performance required for stretchable digital circuit functionality on skin. Carmel Majidi, an associate professor of mechanical engineering and the director of the Soft Machines Lab at Carnegie Mellon, and Mahmoud Tavakoli, the director of the Soft and Printed Microelectronics Laboratory at the
Applications for ultrathin, compliant tattoos include epidermal biomonitoring, soft robotics, flexible displays, and 3D-transferable printed electronics. The findings were published in Advanced Materials in a paper titled “EGaIn-Assisted Room-Temperature Sintering of Silver Nanoparticles for Stretchable, Inkjet-Printed, Thin-Film Electronics.” This collaboration is part of the Carnegie Mellon-Portugal Program (http://www.cmuportugal.org).
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of the University of Coimbra, Portugal have developed a
