Advanced manufacturing of printed and flexible electronics
Towards more sustainable flexible, printable sensors and systems
There is great push to transfer from linear towards circular economy and achieve climate neutral societies during coming decades. Electronics/ICT is one of the priority sectors and need to decrease environmental footprint of electronics is important. Global electrical and electronic waste production is increasing with only tens of percent’s are collected/recycled properly. In addition, global consumption of material resources is expected to be more than double between 2015 and 2050. Our great interest is to explore new more sustainable and recyclable biomaterials including biobased plastics, compostable and recyclable materials in future flexible, printable sensors and systems. This presentation will introduce interactive signage display embedded in foam formed cellulose fiber structures, paper based hybrid electronics as well as utilization of recycled and renewable biobased plastics in structural electronics.
TI²: Tactile Iontronic Intelligence for Wearable Healthcare
Personalized medicine has become extremely popular subjects to explore in both industries and academia recently, in which a variety of wearable and flexible electronic technologies have been emerged to facilitate such transformative changes. As the next phase of personalized healthcare, tactile sensing and intelligence offer a completely new means to obtain body vital signs and health information, where a high-sensitivity, noise-proof sensing mechanism with long-term functionality and wearability can play a critical role in real-world implementation, while the existing mechanical sensing technologies (i.e., resistive, capacitive, or piezoelectric) have yet offered satisfactory performance to address them all. Here, we have first introduced an emerging supercapacitive sensing modality, known as flexible iontronic sensing (FITS), with a variety of material selections for wearable pressure and tactile sensing using an elastic ionic-electronic interface. Notably, the sub-nano iontronic sensing structure offers an extraordinarily high mechanical-to-electrical sensitivity, which is at least 10,000 times higher than its capacitive counterparts, and three orders of magnitude thinner than any existing pressure sensors, with a single-Pascale pressure resolution, achieving high levels of noise immunity and signal stability for a wide range of wearable health applications. In addition, its fabrication process is fully compatible with existing industrial manufacturing and can enable its new utilities in emerging personalized medical and healthcare uses in a foreseeable future.
Sensor Device Architectures and Smart Systems
Printable Tactile Sensors for Soft Electronics and Soft Robotics
Tactile sensors are widely used in the field of soft electronics and soft robotics. Fabrication of the tactile sensors using two-dimensional (2D) or three-dimensional printing (3D) is becoming attractive due to the ability to prepare complex structures through computer aided designs and multimaterial co-deposition. In this talk, I will discuss our research progress on piezoresistive, capacitive, piezoelectric and triboelectric based tactile sensors and their fabrication using inkjet printing or 3D printing methods. We have used transfer printing to prepare piezoresistive tactile strain sensors based on crumpled graphene and nanocellulose, the strain sensors can be integrated into smart gloves which are applicable for rehabilitation. In addition, piezoelectric tactile sensor has been fabricated through the uniquely designed kirigami pattern with 3D printed piezoelectric composites made of barium titanate and polyvinylidene trifluroethylene using direct ink writing. The resultant kirigami pattern endows stretchability of the non-stretchable composite material, and simultaneously achieves planarity by avoiding out-of-plane protrusions during stretching. The characteristic has enabled the pressing or compression mode of the kirigami piezoelectric gait sensor. For the triboelectric tactile sensors, we utilize an extremely stretchable self-healable polyurethane acrylate-based material to fabricate the triboelectric nanogenerator for sensing. The triboelectric active layer and the electrodes are fully 3D printable. In approaching transparent capacitive tactile sensing, we develop inkjet printable gels that enable additive manufacturing of touch sensing arrays and realize sensing of various gestures when the sensor arrays are subjected to dynamic stretching.
Low power electronics for autonomous sensors
High-fidelity and Large-area Flexible Hybrid Sensing System
Combining printed flexible electronics (FE) with high performance silicon chips, known as flexible hybrid electronics (FHE), can bring together flexible form factors, low-cost fabrications and high computational capabilities, thus enabling more innovations for wearable, artificial skins and IoT applications. However, as a heterogeneous system, motion artifacts and noises pose great challenges on designing robust interfaces between FE and silicon. Besides, the FHE sensing system has to tolerate inadequate device yield, reliability and stability caused by the low temperature process and the large-area nature of flexible sensor arrays. Therefore, it is essential to develop design methodologies for large area sensing applications which can suppress the noises in the interfaces and ensure system robustness without relying on highly reliable devices.
To address the noise issue, we prototyped an active electrode (with a thickness <=2 um), which integrates the electrode with a thin-film transistor (TFT) based amplifier, to effectively suppress motion artifacts. To alleviate the device defects, we developed an encoder-decoder design which leverages the sparse statistical characteristics of bio-signals via compressed sensing (CS). Specifically, we use flexible circuitry to implement a simple CS encoder and decode the compressed signal in the silicon side. As a system demonstration, we fabricated the temperature sensor array, shift register and amplifier to illustrate the feasibility of the encoder design using CNT-based flexible thin-film transistors.
Energy Harvesting & Storage
Flexible Battery: Power Solution for Flexible Electronics
Our research focuses on development of flexible energy storage/conversion devices, including supercapacitors, batteries and metal air batteries.
Wearable electronic textiles that store capacitive energy are a next frontier in personalized electronics. We demonstrate a new electrolyte comprising polyacrylic acid dual cross-linked by hydrogen bonding and vinyl hybrid silica nanoparticles (VSNPs-PAA) that addresses all the superior functions and provide an ultimate solution to the intrinsic self-healability and high stretchability of a supercapacitor. Supercapacitors with VSNPs-PAA as the electrolyte are self-healed, achieving an excellent healing efficiency of ~100% even after 20 cycles of breaking/healing. By a designed facile electrode fabrication procedure, they are stretched up to 600% strain with performance enhanced.
In addition, we have successfully fabricated an extremely safe, wearable and rechargeable solid-state aqueous electrolyte based battery with a new hierarchical polymer electrolyte (HPE). The HPE works as both an efficient ionic conductor and a highly effective separator, providing high flexibility, high ionic conductivity as well as the excellent safety performance for the battery. This solid state ZIB exhibits a high energy density (14.6 mWh cm−3 normalized to the volume of the whole device), a high specific capacity of 280 mAh g-1 and high capacity retention of 97% after 1000 cycles. Moreover, this battery exhibits high flexibility and greatly enhanced safety performance.
Hybrid Systems on Foil
TFT Foundry MPG for Display and Sensor Development – Design, Prototype material, Equipment
With the fast growth of demand for IOT and smart sensors, traditional silicon foundries show disadvantages in research cost and mass production. Multi-Project-Glass (MPG) utilizing mature TFT display Foundry capacity would be able to provide a cost-effective route to support research and development. Several different designs can be combined into one mask set to reduce prototype cost for each project. Furthermore, verifications of new materials and new equipment in production line are also available. So far, the MPG project has made progress in photoelectric, tactile, pressure, fingerprint, ion sensors, microfluidics chips and other fields with many universities, enterprises and other partners.
Applied mechanics, reliability and modelling
Emerging technologies
Bio-inspired electronic eye and bio-integrated drug delivery device
Despite recent progresses, significant challenges still exist in developing a miniaturized and lightweight type of artificial vision that features wide field-of-view (FoV), high contrast, and low noise. Meanwhile, the wireless integration of wearable devices with implantable devices can present a new opportunity in the development of unconventional biomedical electronic devices. In this talk, recent progresses in the bio-inspired electronic eye and the wirelessly-integrated bioelectronics will be presented. In the first part, a fish-eye-inspired camera integrating a monocentric lens and a hemispherical silicon-nanorod photodetector array will be presented. In the second part, a bioelectronics device that consists of a soft implantable drug delivery device integrated wirelessly with a wearable electrophysiology sensing device will be presented. These novel types of device are expected to provide new opportunities for the next generation bio-inspired electronics and bio-integrated electronics.
SOFT ELECTRONICS FOR HUMAN-CENTERED ROBOTICS
Internet of things (IoT), robotics, and artificial intelligence (AI) hold the key to Industry 4.0. To stay relevant in the AI age, humans must collaborate and/or even merge with electronics, machines and robots to realize internet of health (IoH), augmented reality (AR), as well as augmented human capabilities. However, bio-tissues are soft, curvilinear and dynamic whereas conventional electronics and machines are hard, planar, and rigid. Over the past decade, soft electronics blossom as a result of new materials, novel structural designs, and digital manufacturing processes. This talk will discuss our research on the design, fabrication, conformability, and functionality of soft bio-integrated and bio-mimetic electronics based on inorganic functional materials such as metals, silicon, carbon nanotubes (CNT), and graphene. In particular, epidermal electronics, a.k.a. electronic tattoos (e-tattoos) represent a class of noninvasive stretchable circuits, sensors, and stimulators that are ultrathin, ultrasoft and skin-conformable. My group has invented a dry and freeform “cut-solder-paste” method for the rapid prototyping of multimodal, wireless, or very large area e-tattoos that are also high-performance and long-term wearable. The e-tattoos can be applied for physiological sensing, prosthesis control, and human-mimetic robots. Examples could range from human-robot interaction to implantable artificial retina. A perspective on future opportunities and challenges in this field will be offered at the end of the talk.
