Transferring nanofiber technology to develop highly protective facemasks for railroad operators

Avalon Nano-Biotech (HK) Limited has provided a donation to the ME department of 3 million Hong Kong dollars to support Prof. Wallace Leung in further developing and commercializing advanced air filtration nanofiber technologies to capture airborne pollutants and viruses (e.g., COVID-19 virus). Alongside with new technology development, Prof. Leung together with Avalon has transferred a nanofiber technology, which has been licensed earlier to Avalon, for the immediate need of developing a highly protective facemask for professionals working in railroad environment. This is especially vital during the current COVID-19 pandemic. A new clean room for class 8 under ISO 14644-1 has been built in MTR Siu Ho Wan Depot in 3 months to accommodate several facemask production lines that have incorporated nanofibers into the facemasks. The produced facemasks are provided to over 17,000 MTR employees in Hong Kong. Protecting the health of MTR employees is very important as they serve nearly 6 million Hong Kong passengers riding the rail daily. This is also the first clean room ever built by the railroad service provider in the world to produce facemasks for their employees. The technology adopted by MTR is based on the nanofiber filter technology developed by Prof. Leung’s R&D group in ME since 2006. The nanofiber facemask has been certified for the ASTM level II standard with PFE (particulate filtration efficiency) and BFE (bacterial filtration efficiency) both exceeding 98% by certifying agency. In fact, the PFE and BFE of the nanofiber facemask are above 99% in the certification testing. Further, the nanofiber facemask can also capture 20-60 nm nanoaerosols with filter efficiency of 95-98%. Also, the facemask can be used in dirty environment with high aerosol loading. Not only the facemasks offer high protection against tiny invisible aerosols and airborne viruses, the pressure drop for the facemasks are relatively low providing comfort to wearers. All these merits are extremely beneficial for railroad operators and professionals. Prof. Leung has also helped to set up quality assurance and quality control to ensure all the produced facemasks in the MTR Siu Ho Wan Depot clean room meet the stringent requirements per ASTM level II certification. This ensures the nanofiber technology is well transferred into a sound and useful product that benefit the Hong Kong community.

Prof. Li Cheng awarded the Second Prize of the Science and Technology Progress Award 2019

Prof. Li Cheng, Chair Professor of Mechanical Engineering of ME Department was awarded the 2019 Second Prize of the Science and Technology Progress Award by the People’s Government of Guangdong Province, China. The prestigious prize is the fruit of long-term collaboration that Prof. Cheng and his team have been undertaking with Midea Ltd, the largest domestic product company in China. During the last two years, Prof. Cheng’s research team has been closely collaborating with Midea through a number of research and consultancy projects, targeting some bottle-necking noise and vibration problems that the company was facing. The project on which the award was granted concerns the development of a complete set of design, analysis and optimization tools on the use of Micro-Perforated Panels (MPP) for sound absorption and their application in a wide range of key products that Media is manufacturing. According to the company’s report, the MPP-based technology has been successfully implemented in a total of 1.6 million Midea’s domestic products, which has up to now secured a net additional income amounting to 1.93 billion RMB.

ME receives donation from Philip K. H. Wong Foundation to support PAED Co-op initiative

The PolyU Department of Mechanical Engineering (ME) received a generous donation from Philip K. H. Wong Foundation for the enhancement of the BEng (Hons) in Product Analysis and Engineering Design programme (PAED) engaging in real industrial learning. The perspective of the PAED programme is to train up our mechanical engineering students on product development and analytical skills. It involves a lot of hands-on and project-based trainings to get our students ready for real industrial participation. In 2019/20 academic year, PAED has launched the “Cooperative Education” (Co-op) option for students to grip the pragmatic knowledge through real-world experiential learning in professional and industrial setting. While we are having more co-op relationships with industrial entities and engaging in more product development trial projects for the students, we are in need of resources to gear up our students before setting off on the Co-op working. That involves an establishment of a product development workshop, where hardware and software facilities are the requisites. Special training on product design and development will be emphasized. Furthermore, students will have the opportunities to practice and elevate their skills through an innovative PAED contest. The department expressed sincere gratitude to Philip K. H. Wong Foundation for donating a funding of HK$1.5 million to sponsor the above Co-op initiative, which will benefit the PAED students in the coming two years.

ME researchers revealed important physical phenomenon in Nature Physics

When we press and pluck the strings of a guitar, it generates different types of acoustic waves. How those waves sound is decided by how we pick those strings and the strings’ nature properties such as length and thickness. The principle here is that wave radiation depends on both the intrinsic properties of the source and the eigenstates of its surrounding environment. This has laid the foundation to explore and exploit various physical phenomena in a wide range of wave systems. The evolving understanding of this paradigm has inspired countless breakthroughs in wave-matter interaction related fields ranging from mechanics and acoustics to optics and photonics. A long-held belief of wave-matter interaction is that an emitter always radiates into and interacts with the eigenstates that exclusively define the surrounding environment. Even in non-Hermitian systems featuring exceptional point(s) where two or more eigenstates coalesce leading to an incomplete eigen-basis in the Hilbert space, this was still deemed to be valid previously as the wave function associated with the missing dimension of the Hilbert space has not been observed in any physical system. Research team led by Dr Jie Zhu, Associate Professor of the PolyU Department of Mechanical Engineering, conducted collaboration with Prof. Ren-min Ma’s team from Peking University, Prof. Li Ge’s team from City University of New York and other colleagues. They show that the above-mentioned century-old tenet can surprisingly break down at an exceptional point. With investigation on difference classic wave systems, the researchers experimentally demonstrated a chirality-reversal phenomenon in a whispering gallery mode cavity where the excited unidirectional wave circulation exhibits opposite handedness to the coalesced eigenstate. This striking yet extensively existed phenomenon were confirmed in both acoustic and electromagnetic wave systems. Their finding, for the first time, reveals that the radiation field of an emitter can become fully decoupled from the eigenstates of its environment. Such counter-intuitive phenomenon transforms the fundamental understanding of wave-matter interaction and enriches the intriguing physics of exceptional points hidden behind source-eigenstate interplay. In acoustics, it could contribute to a board range of research fields, including non-Hermitian acoustics, noise control and abatement. This work has been recently published online on Nature Physics [ “Revealing the missing dimension at an exceptional point”, https://www.nature.com/articles/s41567-020-0807-y ]. Dr Tuo Liu, Postdoctoral Fellow of the PolyU Department of Mechanical Engineering (also a PolyU ME PhD graduate) is the co-first author. Read the full text of paper at https://rdcu.be/b2JlC.

ME MPhil student awarded IEEE MTT-S Undergraduate/Pre-graduate Scholarship 2020

PolyU ME MPhil student Man Ho TSOI was elected to be the awardee of IEEE MTT-S Undergraduate/Pre-graduate Scholarship 2020. Man Ho, under the mentorship of an IEEE MTT-S member Dr Steve Wai Yin MUNG, submitted a research proposal topic titled “Design and Implementation of Surface Acoustic Wave (SAW) device in wireless circuit” which showed high potential for a productive career in RF (Radio Frequency)/Microwave Engineering. IEEE (Institute of Electrical and Electronics Engineers) is the world’s largest professional organization devoted to the innovation and advancement of technology across disciplines. MTT-S (Microwaves and Theory and Techniques Society) is one of the technical societies within IEEE. Undergraduate/Pre-graduate Scholarship Programme is held twice a year with a maximum of ten awardees around the world in each cycle. The scholarship programme encourages students to pursue study and job related to its field. In 2020 Cycle 1, six students from universities in USA, Russia, Spain and China were awarded the scholarship, Man Ho was one of them. 2020 Cycle 1 Awardees (October 2019 Competition) Man Ho is currently pursuing the part-time MPhil degree under the supervision of Dr Yat Sze CHOY in the Department of Mechanical Engineering, the Hong Kong Polytechnic University.

Protecting personal health from impending flu season and Novel Coronavirus

The breakout of the Wuhan virus and serious influenza during the winter months in Hong Kong has raised concerns from the general public. Face masks are worn generally for the prevention of spread of virus and bacteria that cause sickness. Yet, misconceptions about the proper usage of face masks are very common in the community. Ir. Professor Wallace Leung Woon-Fong, Chair Professor of Innovative Products and Technologies of the Department of Mechanical Engineering, who has been studying the science behind masks and developing various combating technologies, suggested a user-friendly way to wear a proper mask. Leung pointed out that face masks are worn by general public and professionals for protection from airborne viruses spread through spit and mucous. Therefore, the outer layer of the mask is hydrophobic (i.e. hate water) so that ‘germs’ carried with water in the spit from others around would not come in contact with the user wearing the mask. On the other hand, the inside layer is hydrophilic (i.e. like water) which absorbs moisture, keeping the user comfortable. Based on the above understanding, he introduced a scientific method to distinguish the inside or outside layer of a face mask for the general public. His method is to simply add water droplets onto the surface of the mask and observe if the droplet ‘rolls up’ similar to that on a waxed surface (moisture prevention layer), or the water droplet soaks into the mask surface (moisture absorbing surface). The moisture prevention layer should be worn outside while the moisture absorbing layer should be worn inside in contact with the wearer. It is also important to test both sides in pursuit of the functionality of the mask. If both surfaces have been tested to have the same property, there is no inside or outside layer to speak of. Therefore wearing the mask with either side is fine, but it is preferred to purchase a better functional face mask. On the other hand, if the two surfaces are different, wearing the mask inside out lead to trapping of viruses and bacteria in the mask, this increases the risk of contact viruses and bacteria. Professor Leung had developed electrostatically charged nanofiber filter with multiple separator layers. The novel PVDF nanofiber filter can capture pollutant particles that are below 100 nm in diameter. It demonstrates much better performance in breathability and filtration efficiency, compared with existing technologies and products, and has a longer shelf life in high humidity up to 90 days. The filter or face mask applying the innovation would be an ideal defense against virus, such as measles, SARS, and other unknown health-threatening viruses during an outbreak. This is because most viruses are negatively charged and the PVDF nanofiber mask is positively charged making virus capture more effective. Media interview by Ming Pao 底層吸水 面層防水 戴錯口罩 病菌有「隙」可乘

ME Student wins in HKIE Student Project Competition 2019

The HKIE-SSC Student Project Competition, organized by The Hong Kong Institute of Engineers (HKIE), is an important annual event to attract HK young generation currently studying in universities to explore safety & health engineering for a touch of both life-critical systems and popular science innovation. The objectives of the competition are to promote safety engineering and science innovation, and to provide an open and competitive platform for engineering students to demonstrate their engineering capabilities and share the learning process in safety regime. This year, a PolyU ME year 3 student, JIANG Jiacong, presented a novel design about improving the testing method of elevator over-speed governor during periodic elevator examination. His innovative idea was acclaimed by the judges and awarded the CIC award. He was the only undergraduate winner in the safety category among other postgraduate awardees. The award ceremony was held in the 25th HKIE-SSC Annual Dinner organized by the HKIE – Safety Specialist Committee on 14 Jan 2020. Over-speed governor (GOV) is equipment to monitor and limit the moving speed of elevator cars. The maintenance and examination are therefore very essential in elevator annual test. However, the testing method of GOV using nowadays is still traditional, inconvenient and complicated with low accuracy, which also includes some safety problems. Therefore, it is highly relevant to develop a safer, more efficient, more accurate and user-friendly solution. Based on the analysis and understanding of existing safety problems, a novel testing device is designed, which can conveniently and safely measure the speed with an optical tachometer, and simultaneously accelerate the governor wheel with an electric disc so as to identify whether the GOV is qualified. Preliminary results show clearly the advantages of this new invention and prospects of being widely popularized. The project was supervised by Dr Xingjian Jing of the Department, who has been actively working on solving various critical engineering problems including system control, engineering noise & vibration, energy harvesting, structural health monitoring, complex system identification, sensing and measuring systems, custom-tailored robotic systems and so on. For Dr Jing’s research and development, it can be referred to www.polyu.edu.hk/me/people/academic-teaching-staff/jing-xingjian/ It is always welcomed for those who wish to realize his/her creative ideas into engineering practices to contact Dr Jing cordially striving for an innovative future. Several undergraduate FYP projects and MSc/PhD projects under his supervision achieved impactful results exposed in media news, prestigious awards and top journal publications in the past years.

ME PhD student awarded Best Paper Finalist in ROBIO 2019

PolyU ME PhD students Jiewen Lai and Kaicheng Huang won the Best Paper Finalist award with the paper entitled “A Learning-based Inverse Kinematics Solver for a Multi-Segment Continuum Robot in Robot-Independent Mapping”, at the 2019 IEEE International Conference on Robotics and Biomimetics (IEEE-ROBIO 2019) in Dali, China from 6 to 8 December 2019. IEEE-ROBIO is one of the most prestigious conferences in the robotic field. It is an annual conference co-sponsored by the IEEE Robotics and Automation Society (IEEE RAS). Continuing with more than a decade of its tradition, ROBIO aims to provide a premier forum for researchers, developers, and entrepreneurs involved in the general areas of robotics, artificial intelligence, and biomimetics to disseminate the latest results and exchange views on the future research directions of the related fields. This year, ROBIO provided 6 best paper awards to the 403 accepted and orally-presented papers from all over the world, and 20 of the accepted papers were peer-nominated as the finalists for those competitive awards. Jiewen and Kaicheng are both under the supervision of Dr Henry Chu in our department. Their research interest includes soft robotics, biomimetic robotic system, robotic manipulation, and machine intelligence.

HKPolyU Racing Team inherits the legend

The HKPolyU Racing Team has finished the 2019 Formula Student Electric China (FSEC) competition on 18 to 23 Nov 2019 at the Zhuhai Airshow Center, China. In the FSEC held in Zhuhai this year, nearly 2,000 students from 54 pure electric fleets and 14 self-driving fleets came here through breakthrough levels. The HKPolyU Racing, the first and only formula racing team, formed by Hong Kong local university students, has been representing Hong Kong to compete in the Formula Student Electric China (FSEC) since 2017. At the FSEC 2019, besides competing in the car’s overall design and technical features, as well as contesting on the racing track its acceleration, control, endurance, and various functions, the team also had to present its business proposal. It was thrilling that the HKPolyU Racing Team ranked 31 out of the 54 participating teams in terms of overall results, which was a step ahead compared to 2018 season and the best percentage amongst the three straight seasons. Achievements of the HKPolyU Racing Team in FSEC 2019 included: ranked 7th in the Business Presentation Event passing all scrutineering checks finished competing in 2 out of 4 dynamic events; skid-pad & autocross   It took the team the whole year to design and manufacture the car. Their dedication and enthusiasm have gained tremendous support from various external parties as well as the University. This year, more than 20 industrialists or organizations offered substantial sponsorships through various means like giving the students financial back-up, sponsoring materials, offering technical advice, providing a testing venue, etc. The team obtained over 2 million HK dollars donations in the past year, and the main donors were as follows:   HKI China Land Limited Kolinker Industrial Equipments Ltd. Ngai Hing Hong Plastic Materials (Hong Kong) Ltd. Dr Hou Lee Tsun, Laurence Hong Kong Productivity Council   Their dream of racing was triggered by 9 PolyU Mechanical Engineering students in 2015, who aspired to construct their Final Year Project on building a racing car for joining a formula competition. Since then, the team of the 9 core members has gradually grown into a team with over 70 students from different disciplines. It was a huge step for the students to spark a racing dream and take to the large-scale annual international competition. Their initiative, aspiration, creativity and endurance are what we really proud of. RECRUITMENT DETAILS

ME researchers discovered universality of droplet coalescence in PNAS

Glancing out a window on a rainy day, your eyes are accidentally caught by a small droplet rolling down the glass, where its “other half” is awaiting… Now, the “dating” is about to begin and the droplet reaches out to another. The moment they touch, a connecting liquid bridge forms and quickly grows – the two droplets then coalesce into a bigger one before you could see clearly what has happened. While you are still wondering why it was so fast, another coalescence has just flashed by… Droplet-droplet coalescence is of essence to numerous natural and industrial processes, for example, rain clouds formation and fuel spray in rocket engines. Nowadays, with the help of high-speed cameras, many experimental scientists have successfully captured the transient coalescence of liquid droplets that cannot be perceived by naked eyes. They discovered that, as the two droplets merge into one, the connecting liquid bridge grows by obeying two distinct rules: it either grows linearly with time when the droplets are smaller (or more viscous) or grows with the square-root of time when the droplets are bigger (or less viscous). To unveil the secret of the different rules governing droplet coalescence, Dr Xi Xia, former research fellow (now Associate Professor of Shanghai Jiaotong University), Mr Chengming He, PhD student, and Dr Peng Zhang, Associate Professor of the PolyU Department of Mechanical Engineering, established a theory that unifies the dynamics of liquid bridge growth. The theory is amazingly simple but innovatively integrates some mathematical techniques, such as integral equation and asymptotic analysis, with some physical insights, such as flow self-similarity and interfacial vortex. This work has been recently published online on PNAS (Proceedings of National Academy of Sciences). [X. Xia, C. He and P. Zhang, “Universality in the viscous-to-inertial coalescence of liquid droplets”, http://www.pnas.org/cgi/doi/10.1073/pnas.1910711116]