This Chip's Got Good CurvesThis Chip's Got Good Curves

chip

A silicon circuit mesh has been wrapped onto a pyramidal-shaped substrate. (Image by Rogers Group, University of Illinois)

Researchers at the University of Illinois (Urbana-Champaign), in collaboration with scientists from Northwestern University (Evanston, IL), Korea University (Seoul), and Tsinghua University (Beijing), are experimenting with curvilinear electronics that they say will be more flexible and versatile than today's planar and brittle semiconductor chips. Based on well-developed, high-performance semiconducting materials such as silicon, the new curvilinear chip can wrap around objects with arbitrary curved shapes--a feat that wafer-based technologies cannot perform. Because of this characteristic, next-generation electronics may be able to accommodate curved body parts, opening the door to a new class of biomedical devices that provide intimate integration between the body and electronics or sensors.As reported by Nanowerk, the strategy combines circuits in optimized, mesh layouts with elastomeric transfer elements that accomplish the wrapping process. "The use of purely elastic mechanics together with hybrid plastic/inorganic circuit meshes enables predictive analysis and high strain deformations, respectively," says John Rogers, professor of materials science and engineering at the University of Illinois and a leader of the research effort. "These aspects represent important distinguishing features compared to similar work performed by other groups."All existing forms of electronics are built on the 2-D planar surfaces of semiconductor wafers or plates of glass, Rogers comments to Nanowerk. "Mechanically flexible circuits based on organic semiconductors are beginning to emerge into commercial applications, but they can only be wrapped onto the surfaces of cones or cylinders--they cannot conform to spheres or any other type of surface that exhibits non-Gaussian curvature. Applications that demand conformal integration, e.g. structural or personal health monitors, advanced surgical devices, or systems that use ergonomic or bioinspired layouts, etc., require circuit technologies in curvilinear layouts."Reporting their findings in Small, the team says that it has developed advanced concepts for conformal wrapping of silicon-based circuits--initially fabricated in 2-D layouts with standard or moderately adapted forms of conventional techniques--onto different curvilinear surfaces. Rogers remarks that his team uses structured silicon membranes with thin polymer/metal interconnects in noncoplanar mesh layouts. "The result embodies combined aspects of concepts recently reported for electronic eye cameras and for stretchable electronics to achieve new and general capabilities for curvilinear electronics on surfaces with nearly arbitrary shapes."MPMN has highlighted other research projects by John Rogers and his team, including in "Implantable Silicon Electronics on Silk Do Disappearing Act," "Researchers Combine the Advantages of Organic and Inorganic LEDs," and the "Emerging Technologies Showcase" webcast.