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Conventional pressure sensitive adhesives (PSAs) are fabricated from soft viscoelastic materials that satisfy Dahlquist's criterion for tack with a Young's modulus (E) of 100 kPa or less at room temperature and 1 Hz. In contrast, the adhesive on the toes of geckos is made of beta-keratin, a stiff material with E at least four orders of magnitude greater(More)
The gecko's remarkable dry adhesive system, consisting of arrays of heirarchically stuctured hairs made from a stiff material , has motivated widespread interest in creating a synthetic dry adhesive whose adhesive properties derive more from its geometry than its bulk material properties. Recently, methods for synthesizing simple hair arrays have been(More)
A hyperelastic pressure transducer is fabricated by embedding silicone rubber with microchannels of conductive liquid eutectic gallium–indium. Pressing the surface of the elastomer with pressures in the range of 0–100 kPa will deform the cross-section of underlying channels and change their electric resistance by as much as 50%. Microchannels with(More)
We propose iSkin, a novel class of skin-worn sensors for touch input on the body. iSkin is a very thin sensor overlay, made of biocompatible materials, and is flexible and stretchable. It can be produced in different shapes and sizes to suit various locations of the body such as the finger, forearm, or ear. Integrating capacitive and resistive touch(More)
High dry friction requires intimate contact between two surfaces and is generally obtained using soft materials with an elastic modulus less than 10 MPa. We demonstrate that high-friction properties similar to rubberlike materials can also be obtained using microfiber arrays constructed from a stiff thermoplastic (polypropylene, 1 GPa). The fiber arrays(More)
Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1 MPa. Geckos possess subdigital adhesives composed mostly of b-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if(More)
We extend soft lithography microfabrication and design methods to introduce curvature sensors that are elastically soft (modulus 0.1–1 MPa) and stretchable (100–1000% strain). In contrast to existing curvature sensors that measure differential strain, sensors in this new class measure curvature directly and allow for arbitrary gauge factor and film(More)
A hyperelastic, thin, transparent pressure sensitive keypad is fabricated by embedding a silicone rubber film with conductive liquid-filled microchannels. Applying pressure to the surface of the elastomer deforms the cross-section of underlying microchannels and changes the electrical resistance across the affected channels. Perpendicular conductive(More)
We introduce a curvature sensor composed of a thin, transparent elastomer film (polydimethylsiloxane, PDMS) embedded with a microchannel of conductive liquid (eutectic Gallium Indium, eGaIn) and a sensing element. Bending the sensor exerts pressure on the embedded microchannel via the sensing element. Deformation of the cross-section of the microchannel(More)
Liquid-phase electronic circuits are patterned on an elastomer substrate with a microcontact printer. The printer head dips into a pool of a liquid-phase gallium-indium alloy, e.g., eutectic gallium-indium (EGaIn) or gallium-indium-tin (Galinstan), and deposits a single drop on a silicone elastomer substrate. After patterned deposition, the liquid-phase(More)