Journal Article

An ultra-lightweight design for imperceptible plastic electronics

Bauer-Gogonea, Simona, Bauer, Siegfried, Kuribara, Kazunori, Schwödiauer, Reinhard, Drack, Michael, Kaltenbrunner, Martin, Yokota, Tomoyuki, Sekitani, Tsuyoshi, Tokuhara, Takeyoshi, Graz, Ingrid, Someya, Takao, Reeder, Jonathan

2013

Overview

Electronic sensor foils only 2 μm thick are extremely light, 27-fold lighter than office paper, durable and flexible and conform to curvilinear surfaces for many innovative applications. Feather-light unbreakable plastic electronics Flexible electronics is emerging as a mainstream technology for smart, mobile, wearable devices and also for biomedical applications. Kaltenbrunner et al . break new ground by fabricating light-as-a-feather virtually imperceptible and unbreakable electronic foils that can conform to any desired shape. The foils consist of organic transistors with an ultra-dense oxide gate dielectric, itself only a few nanometres thick, deposited on ultra-lightweight plastic films, for an overall thickness of just two micrometres. They can withstand repeated severe bending and stretching, can crumple like paper, and work at elevated temperatures and in wet environments. The authors demonstrate that the flexible electronic foil can act as a tactile sensor on a model of the upper human jaw, illustrating the potential for this technology in health care and monitoring. Electronic devices have advanced from their heavy, bulky origins to become smart, mobile appliances. Nevertheless, they remain rigid, which precludes their intimate integration into everyday life. Flexible, textile and stretchable electronics are emerging research areas and may yield mainstream technologies 1 , 2 , 3 . Rollable and unbreakable backplanes with amorphous silicon field-effect transistors on steel substrates only 3 μm thick have been demonstrated 4 . On polymer substrates, bending radii of 0.1 mm have been achieved in flexible electronic devices 5 , 6 , 7 . Concurrently, the need for compliant electronics that can not only be flexed but also conform to three-dimensional shapes has emerged 3 . Approaches include the transfer of ultrathin polyimide layers encapsulating silicon CMOS circuits onto pre-stretched elastomers 8 , the use of conductive elastomers integrated with organic field-effect transistors (OFETs) on polyimide islands 9 , and fabrication of OFETs and gold interconnects on elastic substrates 10 to realize pressure, temperature and optical sensors 11 , 12 , 13 , 14 . Here we present a platform that makes electronics both virtually unbreakable 4 and imperceptible. Fabricated directly on ultrathin (1 μm) polymer foils, our electronic circuits are light (3 g m −2 ) and ultraflexible and conform to their ambient, dynamic environment. Organic transistors with an ultra-dense oxide gate dielectric a few nanometres thick formed at room temperature enable sophisticated large-area electronic foils with unprecedented mechanical and environmental stability: they withstand repeated bending to radii of 5 μm and less, can be crumpled like paper, accommodate stretching up to 230% on prestrained elastomers, and can be operated at high temperatures and in aqueous environments. Because manufacturing costs of organic electronics are potentially low, imperceptible electronic foils may be as common in the future as plastic wrap is today. Applications include matrix-addressed tactile sensor foils for health care and monitoring, thin-film heaters, temperature and infrared sensors, displays 15 , and organic solar cells 16 .

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/301/1005/1007 / Application fields / Applied sciences / Bolometer; infrared, submillimeter wave, microwave and radiowave receivers and detectors / Circuit design / Delivery of Health Care / Design and construction / Elastomers / Elastomers - chemistry / Electronic circuits / Electronics / Electronics - instrumentation / Equipment Design / Exact sciences and technology / Fabrication / Field programmable gate arrays / Fingers / Gold / Heat / High temperature / Hot Temperature / Humanities and Social Sciences / Humans / Infrared Rays / Infrared, submillimeter wave, microwave and radiowave instruments, equipment and techniques / Instruments, apparatus, components and techniques common to several branches of physics and astronomy / Jaw - anatomy & histology / letter / Methods / Models, Anatomic / multidisciplinary / Physics / Plastics - chemistry / Pliability / Polymer industry, paints, wood / Polymeric composites / Polymers / Science / Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices / Sensors / Silicon / Solar cells / Studies / Technology of polymers / Thin films / Transistors / Transistors, Electronic