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Striving for healthy living

Professor Yuguo Li, Professor, Chair of Building Environment, 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 Professor, Chair of 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)

 

Developing Nanorobots for high-precision tasks

Professor Ning Xi (on the right), Chair Professor (Robotics and Automation) of Department of Industrial and Manufacturing System Engineering, HKU 

As scientific probes focus increasingly on the cellular or molecular level, nanoscale tools have become more important than ever.

Unlike the conventional robots being used to carry out repetitive or dull tasks humans do not want to do, such as assembling work, the newly-risen nanorobots take on a distinct role – that of enabling humans to perform tasks that otherwise cannot be achieved.

Professor Ning Xi, Chair Professor of Robotics and Automation at the Department of Industrial and Manufacturing System Engineering, The University of Hong Kong (HKU), is a driving force behind the development of such robots.

Since joining HKU in 2015, he has brought his effort in developing nanorobots to Hong Kong, that can study with high precision of the small and intricate parts of a human cell, like the nucleus, antibody, receptor, DNA, protein, and virus. Further research breakthroughs in the future, he believes, can aid drug development, disease prevention and treatment. “It can provide cures for many more diseases. People will not be only long-lived, but also have a better quality of life,” said Professor Xi, who is the Director of Advanced Emerging Technologies Institute at HKU and the former Director of Robotics and Automation Laboratory at Michigan State University, the United States.

Much more than helping hands

Augmenting human functionality, nanorobots will be needed increasingly in not just medical but also industrial fields. They can operate in a nanoscale environment, which is becoming more prevalent as the key building block of modern electronics - semiconductor chips - have gone downsized in response to the demand for more flexible and less bulky products. “It was like 100 nanometers before, and it has come down to 7 nanometres now. Some even go to 2 nanometres,” said Professor Xi.

Expecting the rise of a whole new manufacturing process using new materials in the future, he said nanorobots will be needed to manipulate novel materials such as carbon nanotube and graphene. Because of its unique properties of thinness and conductivity, graphene is seen as having great potential. It is just one atom thick and has unique electronic properties, leading researchers to believe that graphene semiconductors could replace existing technology for computer chips.

Research has already shown that graphene chips are much faster than existing ones made from silicon. Professor Xi said because of their unique properties, such new substances could be used for the manufacturing of chips and sensors.  “In the future, manufacturing process of nanorobots will play a vital role because you will need them to fabricate, assembly and test in nanoscale,” he said.

In the bio-medical field, nanorobots can serve the vital functions of enabling the discovery of new drugs for various diseases such as cancer and the development of vaccines. It is because the robots can place the drug targets on different antibodies – which a human hand cannot do - and help identify the kind of molecules that works on a particular receptor.

Drug discovery can be done more quickly with the aid of the nanorobots. “We are expecting nanorobots to be a major tool to enable significant breakthroughs in the field of medicine in the future,” said Professor Xi, whose team has engaged in research collaboration with HKU’s Faculty of Medicine. “The medical research has given us the inspiration and motivation to further develop nanorobotic technology.”

 

Professor Ning Xi (on the right) at the Exhibition of Tam Wing Fan Innovation Wing Two

 

 

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 specialised 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 synthesised 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 mice.”

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.”

 

Accelerating the study of the minute units of life

Professor Kevin Tsia, Professor of Department of Electrical and Electronic Engineering, HKU

The study of cells – the basic units of life – is so significant and fascinating that Professor Kevin Tsia has devoted his time to accelerating the development of tools to analyse them.

A breakthrough from his recent research collaboration with the Faculty of Medicine is a new trajectory inference algorithm called VIA. It can process omics data up to 10-100 times faster than existing technologies, making it powerful in handling large-scale single-cell data (more than millions of cells). It can hence discover elusive cell lineages and rare cell fates in a variety of biological processes that can hardly be discovered by other methods, providing hints on how diseases evolve.

Consisting of rich information of single cells at high precision, omics data are crucial for tracking cell transformation to gauge the occurrence and recurrence of diseases, as well as for the purpose of survival analysis and discovery of biomarkers.

“VIA is a very effective tool for managing a huge amount of single individual cells data and allows us to delineate the underlying biology or physics that dictate the health and disease conditions of humans,” said Professor Tsia of the Department of Electrical and Electronic Engineering, who is also the Programme Director of HKU’s Biomedical Engineering Programme.

Some research teams in the US and the Mainland have adopted the VIA and the related computation tools developed by the team for COVID-19 research to track and predict immune responses after infections or vaccinations and the body’s response to treatments.

Combining VIA with imaging tools

Professor Tsia and his team are expecting much more to be uncovered. One direction is to develop a robust system enabling smooth integration of VIA with imaging tools, such as the FACED microscope – an outcome of his earlier research – capable of performing single-cell or live animal imaging at high speed at a level not achieved by existing technologies.“FACED could be one of the many tools we developed that can generate a lot of valuable single cell information. Then you can feed the information into VIA to do the analysis to see how individual cells behave. Thus, we are essentially building an entire pipeline all the way from front-end imaging to back-end computation,” explained Professor Tsia, who was named a Research Grants Council Research Fellow in 2020.

But it will take perhaps several years before a robust system can be developed for that purpose, he said.

Microscopy is his another key research area, with the aim of unlocking information inaccessible by common imaging tools such as MRI and CT Scan. Those tools can capture the image of a big organ, almost even the entire body, but they cannot get the resolution down to individual cells. “This is the missing gap that we can try to fill,” said Professor Tsia.

The availability of VIA and microscopic tools facilitates not just early detection of diseases but is also a boon for the pharmaceutical industry – by speeding up the drug screening process. In the face of the many research possibilities, Professor Tsia knows clearly what his next steps should be. “We are now focusing on the two main areas of blood-based clinical diagnosis and drug screening. If we can use the optical microscope to detect the cancer cells in the blood, then that can create a lot of potential applications in cancer diagnosis and treatment monitoring."

 

Microfluidic device for blood sampling

 

Microscopy image

 

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 commercialisation 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