Biological tissues are soft, dynamic, and water-rich, while abiotic tools are typically rigid, static, and dry. These differences in physical properties have presented challenges for the development of advanced biomedical systems that require interfacing with the human body. In this presentation, I will introduce our recent work on biomimetic soft composites as a platform for engineering bio-integrated devices that can potentially bridge this gap. These synthetic materials capture important structural features of natural soft tissues and exhibit tissue-mimetic reconfigurability, robustness, and functionality, making them advantageous for constructing bio-interfaces. Soft electronic components were also integrated into the biomimetic materials platform, enabling multifunctional systems for physiological sensing and targeted stimulation. Examples of these smart biomedical tools include artificial cartilage and tendons, electroconductive hydrogels, and organ-integrated 3D electronics, which create exciting opportunities in advanced biomedicine.
In native tissues, cells reside in a complex microenvironment (niche) consisting of factors including neighbor cells, soluble factors, extracellular matrices, topological and mechanical signals. Cell niche is critical in maintaining their phenotype and determining their fates and functions. Reconstituting complex cell niche factors in vitro, either individually or in combinations, in a quantitatively and spatially controllable manner, is critical for investigating the interactions between cells and their niches and hence deriving designing strategies for optimal conditions during cell culture applications and optimal scaffolds for tissue engineering applications. Our lab has developed a multiphoton microfabrication and micropatterning (MMM) technology. Here, the technical capability of the MMM platform in fabricating complex protein microstructures and micropatterns with pre-designed topological features, mechanical properties, extracellular matrix, cell interaction molecules and soluble factors, and biomedical applications including cell niche factor screening for phenotype maintenance and engineering cell niche for cell fate determination will be discussed.
Cells can sense mechanical stimuli and convert them to biochemical signals for various specific cellular responses, such as stem cells differentiation, initiation of transcriptional programs, and cell migration. Cell mechanics focuses on the mechanical properties and behaviours of living cells and how cell mechanics relates to various cell functions. Currently, traditional cell mechanics measurement methods are cumbersome, low-throughput, and expensive to deploy. By exploiting microfluidic technology, Dr. Johnson Cui is investigating the cancer cell mechanics and developing an accurate, easy-to-use cell mechanics measurement platform for cell mechanics research and also for cancer diagnosis and therapeutics in the future.
Photonic platforms with multiplexing capabilities are of profound importance for high-dimensional information processing. In this talk, Professor Nicholas X. Fang will present their recent effort on advancing scalable nanoprinting methods compatible with nanophotonic computing platforms. In the first part, Professor Nicholas X. Fang will discuss an efficient and cost-effective grayscale stencil lithography method to achieve material deposition with spatial thickness variation, for spatially resolved amplitude and phase modulation suitable for flat optics and metasurfaces. The design of stencil shadow masks and deposition strategy offers arbitrarily 2D thickness patterning with low surface roughness. The method is applied to fabricate multispectral reflective filter arrays based on lossy Fabry–Perot-type optical stacks with dielectric layers of variable thickness, which generate a wide color spectrum with high customizability. Grayscale stencil lithography offers a feasible and efficient solution to overcome the thickness-step and material limitations in fabricating spatially thickness-varying structures. In the second part, they show that selective ion doping of oxide electrolyte with electronegative metals shows promise to reproducible resistive switching that are critical for reliable hardware neuromorphic circuits. Based on density functional theory calculations, the underlying mechanism is hypothesized to be the ease of creating oxygen vacancies in the vicinity of electronegative dopants due to the capture of the associated electrons by dopant midgap states and the weakening of Al-O bonds. These oxygen vacancies and vacancy clusters also bind significantly to the dopant, thereby serving as preferential sites and building blocks in the formation of conducting paths. They validate this theory experimentally by implanting different dopants over a range of electronegativities in devices made of multiple alternating layers of alumina and WN and find superior repeatability and yield with highly electronegative metals, Au, Pt, and Pd. These devices also exhibit a gradual SET transition, enabling multibit switching that is desirable for analog computing.
Micro/nanostructured materials offer significantly new opportunities for high-efficiency devices and systems for energy harvesting, conversion and storage. There is, however, a tremendous gap between the proof-of-principle demonstrations at the small scale and the intrinsically large-scale real-world energy systems and sustainable applications. In this talk, Professor Yin will give an overview of our research and, more specifically, present our recent development on how structured photonic materials address the challenge of the tremendous power hungry for space cooling and promote photosynthesis and crop yield in greenhouses.
Conventional mechatronic, hydraulic and pneumatic motors and actuators are used for large-scale robots from ≥10 cm to the human size. At the other, nanometric end of the length scale, nano-robots are powered by molecular motors. However, a number of applications in compact environments require robotic devices in the size range of 10 µm to 10 mm, but these are too small to be powered by the conventional mechatronic systems, and too large for molecular motors. Such a length scale ideally suits a few types of high-performance stimuli-responsive actuating materials that are emerging out of a very active research field in the past two decades, with examples including shape-memory polymers and metals, nanoporous noble metals, reactive polymers and liquid-crystal elastomers, carbon-based materials and transitional metal oxides. In addition to high actuating power densities, some of these materials also offer built-in sensory functions such as resistivity responses to mechanical, heat and humidity changes in the environment, and even energy generation capabilities. Integration of these materials and their signal flows in compact designs thus poses a novel strategy for robotics at the micro length scale. This talk will review some recent progress in this field.
Stainless steel (SS) is one of the most extensively used materials in many public areas and hygiene facilities but has no inherent antimicrobial properties. Additionally, the SARS-CoV-2 exhibits strong stability on regular SS surfaces, with viable viruses detected even after three days. Undoubtedly, this has created a high possibility of virus transmission among people using these areas and facilities. Here, this talk presents the inactivation of pathogen microbes (especially the SARS-CoV-2) on SS surface by tuning the chemical composition and microstructure of regular SS. It is discovered that Pathogen viruses like H1N1 and SARS-CoV-2 exhibit good stability on the surface of pure Ag and Cu-contained SS of low Cu content, but are rapidly inactivated on the surface of pure Cu and Cu-contained SS of high Cu content. Significantly, the developed anti-pathogen SS with 20 wt% Cu can distinctly reduce 99.75% and 99.99% of viable SARS-CoV-2 on its surface within 3 and 6 h, respectively. Lift buttons made of the present anti-pathogen SS are produced using mature powder metallurgy technique, demonstrating its potential applications in public areas and fighting the transmission of SARS-CoV-2 and other pathogens via surface touching.
Debate and scientific inquiries regarding airborne transmission of respiratory infections such as COVID-19 and influenza continue. Exposure was investigated under a face-to-face scenario, where people experience the highest risk of respiratory infection. The short-range airborne route was found to dominate exposure during close contact. Based on the fact that most of the outbreaks occurred in indoor environments, we built the link between long-range airborne transmission and short-range airborne route. Results suggest that effective environmental prevention strategies for respiratory infections require appropriate increases in the ventilation rate while maintaining a sufficiently low occupancy.
Precision manipulation of various liquids is essential in many fields, including DNA analysis, proteomics, cell assay and clinical diagnosis, chemical synthesis, and drug discovery. Their divisible, sticky, and sometime infectious features impose, however, great challenges on processing them, particularly when their volume is down to nano-/subnano-liter. A blood droplet from an Ebola patient can for example infect medical workers through the skin. For diagnosis, medial workers have to crash, filter, and purify a patient’s blood sample to obtain the virus’s genetic materials. This series of operations, very often in a fluidic medium, is highly infectious. Moreover, fluids stick to surfaces, which will contaminate containers and handling tools, causing potential dangers if the medical wastes are not properly managed. In this talk, Prof. Wang shall demonstrate how a simple light or fiber touch functions as a “magic” wetting-proof hand to navigate, fuse, pinch, and cleave fluids on demand, being capable of reducing and even replacing the usage of disposable plastics in the biomedical and pharmaceutical industries.
In recent years, there has been a trend towards integrating small, soft and deformable structures into surgical robot systems. Target applications include endoscopy or magnetic resonance imaging (MRI)-guided intervention, where researchers take advantage of soft and flexible robots for their inherent mechanical compliance. However, these flexible robotic systems are often controlled in an open loop or with positional feedback from 3D tracking devices. Not only the real-time feedback of flexible/soft robot configuration or morphology itself is of importance, but also the robot manipulation modelling, as well as its intelligent control, become an area of interest in the field. To this end, this talk will present various robot prototypes, which attempt to resolve unmet clinical and technical challenges for image-guided intervention or surgery, either in strong magnetic field (1.5-3T) by magnetic resonance imaging (MRI) scanner or in confined anatomical space through endoscopy. Machine intelligent approaches, and also the recent advances in continuum robot design and learning-based sensing/control will also be overviewed. These robots have to incorporate with efficient mechanical transmission, thus enabling delicate mechanical force/motion transmitted from actuators to surgical tools in a long and flexible route. The ultimate goal is to provide high-performance control of robotics instruments for safe, precise and effective surgical manipulation. The speaker will not only share his research outcome, but also various difficulties in his up-and-down research journey, from R&D in university, (pre-)clinical trials in hospital, then technology transfer for clinical applications.