Flexible bioelectronics and micro-optical systems

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Bioelectronics and micro-optics are emerging technologies that will significantly impact the future of healthcare and medicine, food safety monitoring, smart packaging, wearable sensors, and public security. Bioelectronics involves interfacing functional biomaterials with microelectrodes, optoelectronic sensors, and semiconductor devices. A wide variety of catalysts (enzymes), biomolecules (proteins, lipids, nucleic acids), micro-organisms and neural cells can be used to provide highly effective molecular recognition and binding capabilities. The electronic and optoelectronic circuitry attached to biological tissue, plants, thin artificial membranes, and textiles should also be mechanically flexible so that the device can conform to the shape of the underlying object. Recent advances in electrically conductive inks (PEDOT:PSS, Au, Ag) have encouraged researchers to explore drop-on-demand printing technology as a viable approach for creating interconnects and electrodes on a variety of bendable and stretchable substrates. Printing technology is also capable of dispensing picoliter droplets of transparent thermoplastic on microcircuit surfaces to fabricate waveguides, microlenses and photonic structures. Preliminary research at Western has shown that electrically conductive graphene and semiconductive graphene-oxide (GO) can be synthesized from inexpensive graphite powders and dispersed in solvents to form printable inks. Once the GO ink is deposited on a substrate the electrical conductivity can be partially restored through thermal reduction using laser-induced heating. This "tunable band-gap" makes thermally reduced graphene-oxide (rGO) a potentially useful material for creating a variety of electronic components (resistors, diodes, transistors) directly on the printed circuits. Laser microfabrication techniques can also be used to imprint nano/micro-scaled patterns on the conductive films, modify the local optical characteristics, or remove excess film and substrate material. Functional materials, advanced manufacturing, and biomedical technologies are all recognized by NSERC as strategic areas that will benefit our country's economy and improve the quality of life for all Canadians. The long-term goal of this research program is to advance the design strategies and fabrication methods used to create the next generation of mechanically flexible, stretchable bioelectronic devices and bio-integrated systems. Success will depend on fundamental studies of the mechanical, electrical and optical characteristics of inkjet-printed electrodes and circuits, and the ability of laser microfabrication to locally alter these properties. The specific research objectives over the next five years are to: (O1) investigate drop-on-demand fabrication and laser micromachining methods to print and locally "tune" the electrical, optical and mechanical properties of graphene-based microstructures; (O2) exploit the principles of mechanical design to enhance the functionality (electrical & optical properties) and stretchability of electrodes and interconnects printed on various flexible substrates (polymers, paper, textiles); (O3) establish methods and guidelines for bio-functionalizing mechanically flexible printed circuits; and (O4) explore innovative applications of printed flexible bioelectronic and optoelectronic circuitry in patient health monitoring, wearable body sensors, smart food packaging, and large area imaging.