Silk Based OFET, OLET, Biologically Active Transistors
Researchers at Tufts University have developed methods to utilize silk fibroin in the fabrication of eco-sustainable, biocompatible and biodegradable transistor based electronic devices and derivatives such as diodes, light emitting diodes, light emitting transistors, capacitors, sensors, and living transistors. Silk-based transistors can be used in biomedical applications both in vivo and in vitro, without having to retrieve the device, as it is resorbable, bioactive and biocompatible. The invention also has applications in the food and security industries, or for any purpose requiring eco-friendly electronic or optoelectronic devices.
In this era of heightened environmental awareness and increasing demand for more eco-sustainable manufacturing processes, one major challenge facing society is moving from an oil-based economy to a green-economy. Almost all electronic, commercial, and industrial products come packaged with a protective “plastic”, which is generally petroleum-based polyethylene, polystyrene, or polyurethane foam. This plastic foam is not biodegradable and it presents a major disposal problem. Furthermore, the contents of the package are of similar origins and with similar issues. In addition to being eco-friendly, the electronics of the future are envisioned as “soft and rubbery”. A step toward flexible, plastic electronics has been made by the demonstration of silicon circuits bonded to elastomeric substrates. Innovative organic electronic and optoelectronics devices, such as organic thin film transistors, organic light emitting diodes and organic light emitting transistors have been fabricated on plastic substrates and integrated with plastic optics.
The realization of eco-sustainability and device flexibility for the electronics of the future may be achieved by merging the fields of biomaterials and organic electronics. The development of bio-based materials is consistent with the principles of green chemistry and engineering, which pertain to the design, commercialization, and use of processes and products that are technically and economically feasible, but also minimize the generation of pollution and the risk to human health and the environment. Keystones for fulfilling such ambitious goals are converging sciences (physical-chemical-engineering-bio-medical) and converging technologies (nano-bio-opto-electro-photo). The thread linking these converging technologies and allowing a new disruptive technological platform, enabling a new generation of biocompatible, biodegradable and eco-sustainable devices may be offered by the natural silk protein produced by the silkworm, Bombyx mori.
Silk-based transistors are fabricated by combining natural silk fibroin protein with organic semiconducting materials in layered or multilayered field effect transistor architectures. The resulting devices include highly efficient film transistors and light-emitting transistors that may be unipolar (p- or n-type) or ambipolar (p-n-type). The silk fibroin can act as an optically transparent, biodegradable and bioactive dielectric layer or as a transparent substrate, and may be used in combination with conventional substrate materials.
The silk-based transistors can be n- or p-type (unipolar) or n-p-type (ambipolar), as well as fully biocompatible, edible, implantable and resorbable in vivo and in vitro.
Silk is a revolutionary material that can outperform plastics, inorganic polymers, foams, and glass and add unforeseen functions to technologies where conventional materials are used.
- It is the strongest natural fiber available
- It is biocompatible, with controllable biodegradability
- It has insulating properties comparable to the best ceramics
- It is >99 percent transparent across the visible spectrum
- It can be manufactured in a variety of shapes and sizes
US Patent 9,142,787, Issued September 22, 2015
Fiorenzo Omenetto, Ph.D., David L. Kaplan, Ph.D., Jason Amsden, Ph.D., Tufts University School of Engineering
Raffaella Capelli, Stefano Toffanin, Michele Muccini, Roberto Zamboni, Valentina Benfenati, Consiglio Nazionale delle Ricerche - Bologna
Tufts reference # T001623