Oct 7, 2022
Striving for healthy living
Professor Yuguo Li, Chair Professor (Building Environment) of Department of Mechanical Engineering, HKU
Overseeing the research cluster on health under the Faculty of Engineering – one of the three strategic research areas supported by the faculty – Professor Yuguo Li works closely with the government to reduce the chances of vertical transmissions of virus in the numerous tall buildings in this densely-populated city.
He has warned of the drainage stacks in high-rises as aerosol factories, potential culprits of transmission of infection, probably not limited to SARS and SARS-CoV-2. In collaboration with the Environmental Protection Department (EPD), a team led by Professor Li had conducted field measurements in some of the infection venues and explore the transmission mechanisms. Professor Li strongly believes that the more than a dozen vertical transmission cases that occurred prior to the fifth wave of the Covid19 pandemic had to do with a chimney effect related to the buildings’ drainage systems, or poorly ventilated drainage pipes. The vertical outbreaks have very likely become very common during the fifth wave.
His research highlights the importance of regular drainage sewerage surveillance. “The pandemic has exposed some of the weaknesses of our building design,” said the Chair Professor (Building Environment) in Mechanical Engineering and Director of the Edge of the Faculty. “As we have seen, that had led to an explosion in the number of cases in the fifth wave. I hope that convinces the community that there is a need for repair, redesign or new systems to be put in place. I think there is very strong evidence for that at the moment.”
The spread of aerosols
Drainage pipes can be infected with the fact that human saliva, excretions are discharged into the pipes, which are then connected to a vertical stack in a high-rise, before being channeled to the public drain on the ground. “During the process, the waste water would have a complex hydro dynamic interaction with the pipes, and droplets are formed. So when the water leaves due to gravity, the fine aerosols stay in the pipe and in between the discharge there are moments where there's no water discharge in the pipe, and those little droplets stay. But we have unfortunately ignored this aspect. The air in those pipes still moves due to the chimney effect and other forces,” Professor Li explains. “Height is a big factor. It can produce a stronger stack effect. Aerosols could thus be leaked into the environment.”
He suggested that a comprehensive study should be conducted to look into the causes of the Omicron onslaught in the fifth wave, and also research be undertaken on what constitutes feasible healthy building design. That will also require multi-disciplinary discussions, for example between engineers and architects.
As a comprehensive university, HKU provides the academic resources and ideal environment for multi-disciplinary ventures, finding answers to problems through joint collaborations. The co-existence of the Medical Faculty and the Engineering Faculty, both among the founding faculties of the university and with a rich tradition in research and application, gives Professor Li much confidence in spearheading advanced, fruitful research.
Wide applications of engineering knowledge
Through joint research, traditional engineering disciplines, such as mechanical engineering, can be applied in various areas, serving various purposes rather than being limited to for example construction alone. Professor Li is hopeful about future breakthroughs in the medical field, or public health, through the development of new engineering skills and technology.
“For example through biomedical engineering, we can get into all aspects of health, by using data, artificial intelligence to track, and discover drugs, or develop new technologies for all kinds of detection of health issues.”
Professor Yuguo Li (in the middle)
Dedicated research for the future world
Dr Paddy Chan, Associate Professor of Department of Mechanical Engineering, HKU
At his Laboratory of Nanoscale Energy Conversion Devices and Physics, Dr Paddy Chan, Associate Professor at the Department of Mechanical Engineering, The University of Hong Kong (HKU), has relentlessly worked on the production of ultra-thin devices with medical and industrial values.
As reported in Nature Communications last year, one of his inventions is the wearable electrocardiogram (ECG) sensor which integrates flexible, ultra-thin organic semiconductors into a flexible polyimide substrate. It is capable of detecting atrial fibrillation. Powered by a button battery, the sensor has outstanding signal amplification properties with a gain larger than 10000, which allows it to detect abnormal electrophysiological signals such as atrial fibrillation beats. A US patent was filed for the innovation.
Conventional portable ECG sensors cannot easily detect the f-wave due to its weak amplitude. For years, Dr Chan has specialized in research in organic field-effect transistor (OFET) as well as electrochemical transistor. His ECG sensor was made possible with the use of his discovery of the staggered structure monolayer OFETs.
He is eyeing extremely thin and hence extremely flexible active layer material of around one over one thousand of the diameter of the human hair. It will be cheap to make because it can be synthesized and cost much less than the common semiconductor silicon material. But still, creating the ideal material is complicated since the fabrication parameters need to be finetuned and there are many parameters involved, he said.
“I am trying to develop a scalable fabrication method so we can make it onto a large wafer and bring it to the industry. If we can really put the OFET to industrial use, you can create a lot of materials or devices, not just in the medical field alone. Large LED screens or displays, for example, can be driven by tiny devices capable of withstanding very high current. You can have large but very flexible screens. ”But he adds there are still lots of bottlenecks to be addressed before his dream materials are widely adopted. “For example, how to do large-area fabrication, commercialization, how to make a material extremely flexible, integrate it onto the human body, or how to use it to send signals coming from the human body. All these are what we are working on and will probably take years,” he said.
Tiny device used for neuro probe
One of his recent research is related to signals coming from the brain. In his experiment, he placed a tiny, flexible electronic neuro probe placed in the brain of a mouse to study the behaviour of the animal by testing the effects of different external stimuli.
The study could enhance understanding of various neuro signals, of which most meanings are unknown. “To many, it’s just some voltage jumping up and down. But in the experiments, you can make the mouse extremely hungry, show it a piece of cheese, and then measure the signals coming from the brain again. The induced spikes may mean it is the part of the response, and these responses can vary among different mouses.”
He is driven by a belief in the immense possibilities offered by flexible materials. But an open mind remains crucial for innovation. “It is like the smartwatch. People may still think a watch is for knowing the time only, and there is no need to use a watch to measure heartbeat or blood oxygen level.”
Novel robotic system to facilitate microsurgery
Dr Kwok Ka Wai (on the right), Associate Professor of Department of Mechanical Engineering, HKU
A joint research team involving the Department of Mechanical Engineering, The University of Hong Kong (HKU) has found a way to improve the procedures for treating head and neck cancer patients.
The research outcome - a novel MR-safe system in miniature size, with compliant architecture and five degrees of freedom - enables safe and dexterous laser ablation within the confined spaces of the oral and pharyngeal cavities. Leading the engineering research team is Dr Kwok Ka Wai, an associate professor from the Department of Mechanical Engineering, who collaborated with HKU’s Faculty of Dentistry, and the Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, CUHK.
Recently published in the journal Science Robotics, the outcome marks the beginning of more applications for the treatment of a wide range of patients afflicted with head and neck cancer, i.e. cancers in areas including the oral cavity, laryngopharynx, nasopharynx and nasal cavity, which is the seventh most common cancer in the world causing 450,000 deaths every year.
Unlike the traditional treatment approach involving the use of bulky and rigid laser manipulator, the soft robotic manipulator for transoral laser microsurgery is guided by intra-operative magnetic resonance imaging (MRI). The MRI environment allows for evaluating 3D ablation margins alongside thermal distributions in real time, protecting critical neurovascular structures while ensuring adequate ablation margins. But the confines of the MRI bore and its strong magnetic field (1.5/3T) means conventional metallic robot components cannot be implemented. Instead, the novel soft robotic manipulator driven by hydraulics is fit for the job.
Dr Kwok said the complexity and rigidity of the traditional method drove the latest innovation. “With the current conventional approach, it is challenging for surgeons to assess the laser ablation progress during surgery, which is essential to ensure that surrounding healthy tissue is preserved, particularly the muscles for speech and swallowing. Moreover, the current lasers are also delivered through rigid and straight instruments which can put patients in extreme neck extension.”
On the contrary, the new MRI-compatible robot integrated with a laser fibre can direct energy delivery to the target lesion through a patient-specific dental anchorage in the oral cavity, enabling surgical guidance under the MRI.
Creating even smaller robots
Dr Kwok is working on scaling down the robot size further to facilitate endoscopic applications so that mechanical transmission can happen in minimally invasive surgery for different body organs, for example, those attacked by cancer cells. “We can treat the earliest stage of cancer in the digestive system, for example, in the colon, rectum, stomach, esophagus or even bladder.”
Dr Kwok has been working for seven years on robotic systems that can operate in an environment with extremely strong magnetic fields. Aiding that effort was the discovery of positional markers, described by Dr Kwok as the GPS within the MRI system, through collaborations with the university’s Department of Diagnostic Radiology.
Dr Kwok also enjoys close collaborations with counterparts at Johns Hopkins University. “They have an experienced team in developing various kinds of robotic systems for surgical applications. We shared a lot of insight regarding the surgical workflow.”
The vibrant research community at HKU comprising clinicians, radiologists, engineers and other scientists is another important source of support, as is the university’s Technology Transfer Office which helps with seeking backing from potential investors. “Through commercialization or spin-offs, we can sustain the research and carry out further clinical trials towards real clinical applications,” said Dr Kwok.
Demonstration of novel robot system for MRI-guided Transoral Laser Microsurgery
Soft robotic manipulator for Intra-operative MRI-guided transoral laser microsurgery
MR thermometry to precisely monitor the tissue ablation