Epidermal electronics with advanced capabilities in near-field communication

We demonstrate materials, mechanics designs and integration strategies for near fi eld communication (NFC) enabled electronics with ultrathin construction, ultralow modulus, and ability to accommodate large strain deformation. These attributes allow seamless, conformal contact with the skin and simultaneous capabilities for wireless interfaces to any standard, NFC enabled smartphone, even under extreme deformations and after/during normal daily activities. Detailed experimental studies and theoretical modeling of the coupled mechanical and electromagnetic responses of these systems establish foundational understanding of their behavior. These materials and device architectures have potential for utility in other types of radio frequency (RF) electronic systems and for use on other organs of the body. Devices that offer capabilities in near fi eld communication (NFC) appear increasingly in applications that span the banking, [ 1–3 ] medical, [ 1,2,4–7 ] military, [ 5,6,8 ] transportation [ 1,5,6 ] and entertainment industries. [ 1 ] In fact, recent projections suggest that by the end of 2014, more than 150 million mobile devices (i.e. smartphones, laptops, etc) will support ability to interface to various NFC components, currently available in hard or fl exible plastic packages and designed for use in free-standing forms or as stickers for mounting onto various objects. [ 1–3,5–9 ] More recent embodiments include wristbands, [ 4 ] bracelets [ 7 ] and tapes, as initial steps to wearable devices. [ 8,10 ] Here, we report materials and mechanics designs that allow NFC devices to be rendered in stretchable, ultrathin formats with physical properties that resemble those of the epidermis, for natural and impercetible integration directly with the skin. [ 10 ] Thin NFC die connect to stretchable radio frequency (RF) antennas on low modulus elastomer substrates, to yield, ‘epidermal’ systems that mount on the skin like temporary transfer tattoos. [ 10–16 ] Experimental measurements of the resonant frequency and mechanical