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Wearable Technology Insights
Posted on August 19, 2016 by  & 

Customized functional devices attached directly on skin

Everyday devices have become small enough to be embedded into fabrics, work as accessories or be attached directly to the user's body on skin. Particularly epidermal electronics are promising as they are always available and expand the sensing modalities of current mobile and wearable devices by sitting directly on the skin which facilitates direct access to users' biomedical signals.
However the manufacturing of epidermal electronics is expensive and requires materials and fabrication processes that are limited to the medical domain and materials sciences. Researchers have sought to expand such on-skin devices from medical purposes to every day user interaction.
Microsoft Research and MIT have joined to created DuoSkin. DuoSkin is a fabrication process that enables anyone to create customized functional devices that can be attached directly on their skin. Using gold metal leaf, a material that is cheap, skin-friendly, and robust for everyday wear, researchers have demonstrated three types of on-skin interfaces: sensing touch input, displaying output, and wireless communication. DuoSkin draws from the aesthetics found in metallic jewelry-like temporary tattoos to create on-skin devices which resemble jewelry. DuoSkin devices enable users to control their mobile devices, display information, and store information on their skin while serving as a statement of personal style. The team believes that in the future, on-skin electronics will no longer be black-boxed and mystified; instead, they will converge towards the user friendliness, extensibility, and aesthetics of body decorations, forming a DuoSkin integrated to the extent that it has seemingly disappeared.
DuoSkin's three-step workflow. Step 1: (a) Sketching skin circuitry with graphic design software. Step 2: (b) Fabrication, which includes (c) creating stencils of the circuitry, (d) applying gold leaf as the conductive material, and (e) mounting electronics. Step 3: (f) After completing the circuitry, apply the DuoSkin device to the user's skin through water-transfer.
Using DuoSkin, the team created on-skin input elements that resemble traditional user interfaces, such as buttons, sliders, and 2D trackpads.The 2D touchpad uses row-column scanning in a two-layer construction that isolates horizontal traces from vertical traces. They fabricated the two layers separately and then applied and overlaid them onto skin.
DuoSkin brings soft displays onto the skin, enabled through the ink-like qualities of thermochromic pigments. These displays have two different states and color change is triggered when heated beyond body temperature. Displays can also be separated into designated parts. To activate color changes on their displays, the researchers fabricate resistive heating elements underneath the thermochromic layer.
To exchange data across on-skin interfaces, communication needs to be wireless. DuoSkin devices communicate using NFC, whose tags comprise a chip that connects to a coil. This coil is fabricated using gold leaf, customized to various shapes and sizes.
Source and top image: MIT Media Lab
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