On 14 Dec 2017, over 60 researchers congregated at the Institute of Materials Research and Engineering (IMRE) for a half day workshop on Wearable Technologies that was jointly organized by HIFES of NUS and IMRE of A*Star.  The workshop was opened with welcome speeches by Prof Aaron Thean, NUS HIFES Director and Dr. Chiam Sing Yang, acclaimed scientist from A*Star.

In the workshop, 12 NUS and IMRE principal investigators presented and discussed the diverse flexible electronics research topics:

• Filatronics and wearable efforts in IMRE
• Hybrid flexible electronics initiative in NUS
• Printable technology and solutions based processing as the platform for wearable applications
• Flexible and wearable materials including low temperature 2D materials and polymeric materials
• Nanoimpirnt and nanofabrication related support technology
• Flexible nanogenerators and photocatalysis devices
• Flexible magnetic memories and THZ emitters

The workshop has definitely opened up opportunities for future collaborations for both NUS professors and IMRE researchers in the area of wearable technology.

At the invitation of HiFES, Professor Debashis Chanda from the University of Florida presented on Bio-inspired Uncooled Multi-Spectral Infrared Imaging with mK Range Temperature Resolution on 12 Dec at the Electrical and Computer Engineering Department of NUS. He started off the talk by sharing on the applications of Nanophotonic that spans space exploration, aerospace, epidemic screening, security, energy saving, electronic inspection and more. The market value of IR imaging market is estimated at $11.36b by year 2022.

He continued to touch on the limitations of present infrared (IR) detection techniques; which are due to the absence of spectroscopic or “color” detection/imaging abilities.  At present all cooled and uncooled MWIR and LWIR detectors are being “bucket” detectors generate integrated spectral images in the binary color format (choices of any two pseudo colors).  Prof Chanda indicated that very little research work has been performed on frequency selective detection to-date and pointed the audience to see the natural world where one would find many animals are found with the ability to see over multiple spectral bands in the visible as well as in the infrared domain. Mantis shrimp eye is an example of a complex eye which is comprised of an elegant 12 channel spectrum sampler that spans the range 300-750 nm, with spectral bandwidth of around 40 nm. These are among the sharpest spectral sensitivities in the animal kingdom. The key aspect of their eye is “biological light funnel” apparatus which collect light over a wide angle with near perfect efficiency. Another biological masterpiece is pit vipers that have heat-sensitive membranes that can detect the difference in temperature between a moving prey—such as a running mouse—and its surroundings on the scale of milli Kelvins. Their infrared eye (“the pit”) has unique abilities to scatter visible light away and transmit only a band of infrared light which reduces background noise substantially.

HiFES Director, Prof. Aaron Thean was invited to be a keynote speaker for the Emerging Technology Forum held at the NUS Shaw Foundation Alumni House on  MediaTek Innovation Day. The title of the talk was “Novel materials + Novel integration = Novel electronics”.  The audience was certainly captivated by Prof. Thean’s vivid sharing of his  “exciting research experience” in making novel electronic systems with novel materials through novel integration.

At the end of the talk, Prof. Thean shared about the HiFES research consortium partnership programme and sent an open invitation to the staff of MediaTek Singapore to participate in research collaboration.

“Flexible Ideas in the Making. Better Things Ahead.”

HiFES was at the Business and Technologies Insight Forums Seoul from 19 to 21 September 2017. Professor Jerald Yoo presented on HiFES research team’s fresh approach to flexible electronics with Large-Area Skin-Conformal Natural Interfaces in Self-Aligning Platform.

Companies with interest in the project can touch base with us via email: hifes@nus.edu.sg

Flexible Ideas in the Making. Better Things Ahead.

The flexible and wearable electronics system is an emerging technology for next-generation electronics. This type of electronics system can geometrically accommodate large mechanical deformations without imparting significant strains and stress in the materials from which it is constructed. Potential applications of this technology include flexible sensors, communicative packaging, transmitters and new photovoltaic and microfluidic devices, as well as areas of medicine and athletics for which flexible and conformable electronics are required.

Computational Mechanics studies reveal many of the key underlying aspects of these systems and can establish important design criteria concerning device failure. For example, results are used to indicate the maximum strain or stress in a system, or the critical strain for buckling, etc. Furthermore, studies are made to optimize mechanics and materials for circuits that exhibit maximum stretchability.

In this talk, Dr. Liu shared how in the current study, numerical simulations are used for investigations of materials and system designs for flexible electronics devices, which have excellent mechanical flexibility and make them attractive as wearable devices. The new designs are possible to build high performance circuits that are not only bendable but are also, in some cases, reversibly stretchable, with elastic responses to compressive and tensile strains of near to 100% or more. In addition, the application of computational mechanics is a path to build high performance silicon complementary metal oxide semiconductors central to consumer electronics.

Dr. Liu also shed light on the mechanical designs that remove any significant dependence of these properties on strains associated with bending, folding, draping and other modes of deformation. The talked ended with open floor discussion with the conclusion that computational studies are central to discovering the essential features of the materials and mechanics aspects that underlie the behaviour of flexible electronic systems.

On 3 Aug, HiFES was honoured to have the presence of Globalfoundries Visiting Professor, Takao Someya from the Department of Electric and Electronic Engineering, University of Tokyo to give a flexible electronics presentation on breathable on-skin sensors for long term health monitoring.

The talk is a follow on sequence to first part of the flexible electronic thematic talk by Prof Someya in 2016 on wearable electronics. Below are some recaps of his last presentation:

• how the significant number of wirings were achieved for the E-Skin system
• how Stretchable Organic Integrated circuit were formed by special fabrication and simple printing process without adverse impact on the high conductivity requirement with the use of the New Printable Elastic Conductors

On 22 Jun 2017, NUS HiFES invited Wallace C.H. Choy, the professor from the Department of Electrical and Computing Engineering of The University of Hong Kong to share his recent study on the New Schemes of Room-Temperature Solution-Processed Metal Oxide Semiconductors and Transparent Flexible Electrode for High Performance Optoelectronic Devices at the Faculty of Engineering in NUS.

Noted that Transition Metal Oxides are promising materials for carrier transport layers because of their good electrical properties, stability, and optical transmission, Prof Wallace and his researchers explored the room-temperature solution approaches for forming various metal oxides amid the fact that high temperature evaporation and sputtering are commonly used for forming metal oxide semiconductors:

• The team proposed and demonstrated several low-temperature solution-processed approaches for forming transparent and efficient metal oxide-based carrier transport layers including electron and hole transport layers. With the incorporation of metal nanoparticles, the electrical and optical properties could be enhanced. The interesting features of the novel carrier extraction layers are low temperature, solution process and water free for high performance optoelectronics such as OSCs with power conversion efficiency (PCE) of 10.5%.
• They also developed some room-temperature processed Ag nano-network which can serve as transparent flexible electrodes.
• With the knowledge of solution processed organic and inorganic materials, different approaches for highly stable and efficient perovskite SCs were proposed with no hysteresis and most recent PCE of 20.5%.

HiFES is pleased to have Professor Ali Javey from the Department of Electrical Engineering and Computer Science (EECS) of University of California at Berkeley to present his research group’s recent advancements on fully-integrated perspiration analysis system that can simultaneously measure sweat metabolites, electrolytes and heavy metals, as well as the skin temperature to calibrate the sensors’ response on 3 May 2017.

The seminar room was packed to the brim with the NUS professors, research fellows, post graduate students and companies. In the talk, Prof Ali shared how the group has bridged the technological gap in wearable biosensors by merging plastic-based sensors that interface with the skin, and silicon integrated circuits consolidated on a flexible circuit board for complex signal processing. The talk was well received by the audience with overwhelming questions from the floor.

In conclusion, the wearable sensor devices have been proven to measure the detailed sweat profiles of human subjects in their prolonged indoor and outdoor physical activities and infer real-time assessment of the physiological state of the subject. Hydration status, glucose monitoring and cystic fibrosis diagnosis are amongst a few such cited examples of the real-time assessments. The integrated wearable and flexible electronic sensing platform has enabled wide range of physiological and clinical investigations and will certainly open up a new field abound with opportunities alongside the many challenges to be overcome.