Emerging Materials for Flexible and Printable Sensors and Electronics
"All-Printed Organic Thin-Film Transistors with Short Channel Length for Sensing Applications"
Advanced Electronics and Photonics Research Centre, National Research Council Canada, Canada
In this talk, innovative printing methods will be introduced for the fabrication of all-printed organic thin-film transistors (OTFTs) with short channel lengths. By controlling the interaction between ink and substrate, a sub-micrometer gap between two electrodes is achieved while using direct inkjet-printing with 10 pl droplets. We also demonstrate that a printed silver ink can partially dissolve an un-crosslinked SU-8 interlayer, resulting in the formation of a concave confining structure during post-printing treatment. This optimization of the ink-substrate interaction during printing and post-printing treatments enabled a reduction in printed silver electrode line width of more than ten times. Despite the reduction in line width, a high thickness-to-width aspect ratio was achieved which maintains the lower line resistance of the as-printed feature. This unique method of achieving narrow printed features demonstrates the importance of ink-substrate interaction, further investigation of which could enable significant advances in TFT sensor device fabrication. The integration of all-printed OTFTs with sensor materials and devices has the exciting potential to generate a multi-functional sensing platform for large area electronics.
Disposable, Implantable and Biocompatible Sensors Technologies
"Human gas sensing capsules for diagnosing gut disorders "
University of New South Wales, Sydney, Australia
Ingestible sensors are rising as the next most important medical devices for monitoring of human disorders, providing invaluable information regarding different biomarkers of the gut. In this talk, the history of the development of ingestible gas sensing capsules will be presented. This gas sensing capsules have applications in diagnostics of gut disorders and assessing dietary impacts. These capsules leave the body after normal bowel transient and, during this time, transmit information about the gas profiles in different segments of the gut. The capsules consist of gas sensors, electronic circuits, small-sized harmless batteries and telecommunication components that operate within a safe commercial band. The capsules allow accurate measurement of the concentrations of vital gases of O2, H2 of CO2 and also temperature. Animal and the first phase of human trials have been successfully completed and the public domain available outcomes of these trials will be presented in the talk. The observed phenomena using the capsule can potentially revolutionise fields of gastroenterology and food sciences.
Sensor Device Architectures and Smart Systems
"Detectors and light-sources for optical spectroscopy: from 3D-printed light-sources to self-powered sensors fabricated on polymeric substrates, and from there on to IoT-enabled smart systems"
University of Waterloo, Waterloo, Ontario, Canada
We are developing detectors to sense the visible part of the spectrum. We are also developing light-sources that generate spectral signals from micro-samples introduced into battery-operated micro-plasmas. The microplasmas are coupled to a portable, fiber-optic spectrometer and this combination (or system) can be thought of as a “multi-parameter sensor” for the UV and the Vis parts of the spectrum. Initially, our Micro Plasma Devices (MPDs) were fabricated using technologies borrowed from the semiconductor industry (e.g., photolithography and micromachining). To reduce fabrication costs and to enable rapid prototyping, we fabricated Micro Plasma Devices using 3D-printing of polymeric materials. We also fabricated (and continue to characterize) a relatively-inexpensive self-powered detector on a flexible polymeric substrate. The detector responds in the visible part of the spectrum. To enable portability for chemical measurements on-site (i.e., in the field) we often used a smartphone for data acquisition and signal processing, thus enabling sensor-systems to be placed on the Internet of Things (IoT) and, potentially, to be employed in Society 5.0 applications. To further facilitate use on-site (i.e., in the field), portable spectrometers with a short focal length must be used. But as spectrometers get smaller, spectral overlaps (often called spectral interference effects) arise. To address them, we employed Artificial Intelligence (AI) methods using Artificial Neural Networks (ANNs) and Deep Learning approaches, thus (in many respects) making sensor-systems smarter. In this presentation, such developments will be described in some detail and future prospects will be outlined.
Low power electronics for Autonomous Sensors and IoT
"Low power CMOS inverters based on printable inorganic thin-film transistors"
Printable Electronics Research Center, Suzhou Institute of Nanotech and Nanobionics, Chinese Academy of Sciences, Suzhou, China
Low power electronics are typically achieved by CMOS circuits which require both p-type and n-type transistors. However, making CMOS electronics with solution type semiconductors has met great difficulties because no printable semiconductor materials are good at both p-type and n-type. In this paper, we demonstrated two approaches which enabled printable CMOS inverters with low static power consumption. One approach was to tune the polarity of as-printed p-type carbon nanotube (CNT) thin-film transistors (TFT) into n-type, so that a CMOS-like inverter can be constructed by two CNT-TFTs which has achieved low power consumption of 0.3 μW. Another approach was to combine a p-type CNT-TFT with a n-type metal oxide TFT to construct a CMOS inverter which demonstrated low power consumption of 0.4 μW. Both approaches were based on solution type inorganic semiconductor materials and therefore printable, which lay the foundation for printed low power electronic circuits.
Energy Harvesting, Storage and Actuation
Head of Smart Electronic Materials and Systems Group, University of Southampton
Abstract coming soon
Hybrid Systems on foil, heterogenous integration and Packaging
"Flexible hydrogel based wearables for continuous monitoring of biochemicals in sweat"
Dr. Guozhen Liu
Australian Research Council Future Fellow and Senior Lecturer at The University of New South Wales, Sydney Australia
Wearable electronic devices capable of real-time monitoring of key analytes in sweat provides a point-of-care testing to manage the health status and performance of individuals. It is noted that sampling human sweat, which is rich in physiological information, could enable non-invasive monitoring. Given this background, development of a smart sweat-based electronic sensor on a soft substrate is a promising approach for fabricating the wearable health monitoring device. Hydrogels, being similar to biological tissues, have attracted great attention in flexible wearables due to their soft and biocompatible properties. However, these kinds of materials are weak and fragile, which limit their wide application in flexible electronics. Recently, a combination of hydrogels with soft or solid materials has shown to achieve acceptable levels of rigidity and functionality in comparison to their artificial counterparts. Recently, significant effort has been invested in detection of biochemicals in sweat such as glucose, lactate or hormones. By integrating with nanotechnology, biosensors as the analytical devices for the detection of an analyte, that combines a biological component with a physicochemical detector, have demonstrated huge potential for biochemical sensing in sweat. In this talk, Liu will summarize her recent research highlights on development of functional hydrogel based flexible substrates towards the development of wearable sweat-based devices for real time detection of biochemicals.
Theoretical Studies and Modelling of Flexible, Stretchable and Printable systems
"Design of bendable high-frequency circuits based on short-channel InGaZnO TFTs"
Sensor Technology Research Centre, University Of Sussex, UK
Conformable systems operated in close proximity to the human body, or fabricated on large-area plastic substrates enable new applications including smart implants, and electronic textiles. A unique requirement of flexible systems is the need to optimize their electrical and mechanical performance simultaneously. In particular, flexible sensor conditioning and transceiver circuits, insensitive to bending, are required. Thin-film transistors (TFTs) based on amorphous InGaZnO have the potential to enable such circuits. However, while InGaZnO TFTs can be fabricated on temperature sensitive plastic foils, provide carrier mobilities >10 cm2/Vs, and demonstrated functionality when bent to radii as small as 25 μm, they also suffer from certain limitations: First, only n-type devices are available which restricts the number of possible circuit topologies. Second, the electrical performance parameters shift when the TFTs are exposed to mechanical strain. Third, the use of flexible free-standing substrates requires fabrication tolerances complicating the realization of small features essential for fast transistors. Finally, a trade-off between the parasitic overlap capacitance and contact resistance is required as these parameters determine the TFT’s frequency performance, but cannot be minimized at the same time.
Here, the scaling behaviour of flexible InGaZnO TFT is modelled to enable the realization of optimized high-speed transistors. The model is validated using AC measurements of flexible TFTs with channel length down to 300 nm, and enabled the fabrication of TFTs with transit frequencies of 135 MHz, and maximum oscillation frequencies of 398 MHz. In a next step, circuit design principles and SPICE simulation models for the design of InGaZnO TFT circuits, considering electrical and mechanical effects, are presented. These led to various circuits such as fully flexible amplifiers with a gain-bandwidth-product >9 MHz.
Emerging Applications (e.g. e-textile, IoT, smart cities, Health monitoring, soft robotics, etc.)
"Engineering organic electronic materials for the development of smart textiles"
Department of Bioelectronics, Ecole Nationale Superieure des Mines de Saint Eitenne, CMP-EMSE, MOC
In the 21st century, consumers are rapidly gaining access to a novel suite of wearable electronic devices such as smart watches, glasses and garments. These technologies promise both comfort and ease of use, as well as an access to a wealth of health-related information. Advances in the field of electronic textiles, and recent achievements in organic electronics, have enabled the development of new flexible and conformable technologies that can perform the same sensing as current solid-state devices, for a fraction of the cost. Such progress relies on the subtle engineering of organic materials to model their properties in functional devices. The sustainable potential of using organic ionic and electronic conducting materials in wearable monitoring systems has yet to be demonstrated. In cutaneous applications, the use of such organic materials as electrodes lowers contact impedance with the skin resulting in higher quality recordings compared to metal–based electrodes. Combining these materials with textile structures reduces the mechanical mismatch at the interface with the skin, which enables the recording of electrophysiological activities for long time intervals with an enhanced signal to noise ratio. Traditional and non-traditional direct patterning techniques allow the selective deposition of organic materials onto different kind of fabrics. Therefore, the integration of organic electronics and the textile platform provides low-cost and tailored solutions in interfacing smart devices with the human body.