Laboratory of Advanced Microfluidic Systems


Our past efforts on promotion the education on biotechnology are listed below. Here, we would like to sincerely acknowledge the support from the Office of Education Development and Gateway Education via a Teaching Development Grant for both the laboratory module development and facilitating students' term projects as shown below.

Laboratory 1: Determining Human Blood Type by Non-Invasive Genetic Analysis  

Objective: To apply the polymerase chain reaction (PCR), the gel electrophoresis and the restriction fragment length polymorphism (RFLP) to identify the genotype of human cheek cells for their ABO blood group.

Background: The ABO blood group system was discovered by Karl Landsteiner in 1900.  An individual's blood group can be determined by the antigens expressed on red blood cells, in which the antigenic properties can lead to red blood cell agglutination, organ failure, and even death (Yamamoto 2004).  Blood group antigens (A and B antigens) are terminal sugars found in surfaces of red blood cell membranes.  The enzymes adding these terminal sugars are the transferases, coded by the ABO gene with three types of alleles inferred from classical genetics: i, IA, and IB.

The precursor to the ABO blood group antigens, present in people of all common blood types, is called the H antigen.  The A gene codes for production of a galactosaminyl transferase required for the attachment of N-acetylgalactosamine to the H antigen expressing on red blood cells, while the B gene codes for galactosyl transferase that can attach D-galactose to the H antigen.  If a blood sample from an individual can join only one of these sugars to the H antigen, the A and B blood types will be observed accordingly.  Both enzymatic reactions are possessed in an individual with the AB blood type.  Individuals failed to produce any of these functional proteins will have the O phenotype.


Laboratory 2: Mammalian Cell Culture and Immunostaining  

Objective: This laboratory is designed to expose students to cell culture laboratory environment and introduce fundamental concepts and techniques of mammalian cell culture. We also aim at providing students opportunties 1) to understand the basic knowledge about cell culture, 2) to learn the primary operations for cell subculture, 3) to be acquainted with the basic knowledge of cell cytoskeleton, and 4) to master the basic operation of immunostaining.

Background: Cell culture is one of the major tools used in cellular and molecular biology, providing excellent model systems for studying the normal physiology and biochemistry of cells (e.g. metabolic studies, and aging), the effects of drugs and toxic compounds on the cells, and mutagenesis and carcinogenesis. It is also used in drug screening and development, and large scale manufacturing of biological compounds (e.g. vaccines, and therapeutic proteins). The major advantage of using cell culture for any of these applications is the consistency and reproducibility of results that can be obtained from using a batch of clonal cells.

The cells we culture are either primary cells (derived directly from the source, undergo senescence within a few passages) or cell lines (cells that have been transformed so they can keep dividing while maintaining the same phenotype).  It is best to use cell lines up to the passage recommended, though, since repeated passaging can eventually lead to senescence or other phenotypic changes.
Cells must be taken care of properly so they can stay happy and give you good, consistent results! This includes keeping them contamination-free, well fed, and in the proper atmospheric conditions. 

Immunostaining means using an antibody-based method to detect a specific protein in a sample. The term immunostaining was originally used to refer to the immunohistochemical staining of tissue sections, as first described by Albert Coons in 1941. Now however, immunostaining encompasses a broad range of techniques used in histology, cell biology, and molecular biology that utilize antibody-based staining methods.


Laboratory 3: Analysis of Components in Condensed Loquat Extract  

Objective: To quality the Menthol content in Pipa Gao using GC-MS with Perkin Elmer Elite-5MS column.

Background: Pipa Gao is a traditional Chinese cough syrup which is widely used for short-term relief of minor mouth or throat irritation or minor sore throat. Among a blend of a wide variety of herbal ingredients, one active ingredient in Pipa Gao is Menthol, which may exist as one of
the eight possible stereoisomers.

Gas chromatography/mass spectrometry (GC-MS) is a very useful instrumental platform for identification and quantification of chemical composition of an analyte. The gas chromatograph separate the analytes while the mass spectrometer response reflects the amount of different compounds in the sample. In this experiment, we will demonstrate to use of GC-MS to verify and quantify Menthol content in the Pipa Gao. Prior to analysis using GC-MS, menthol will first be extracted into an organic solvent, Dichloromethane (DCM), using liquid-liquid extraction. Liquid-Liquid extraction is a basic chemistry laboratory technique by which a compound is pulled from solvent A to solvent B where solvents A and B are not miscible, as a result of difference in the relative solubility of the compound in the two solvents. In this case, menthol is “pulled” away from water into DCM before it can be put into the GC-MS for analysis.



List of Projects on Biomedical Device Analysis


Total Knee Replacement (1)
When the various bone and joint dysfunction to severe that drug or rehabilitation treatment fails, artificial joint replacement will be able to significantly reduce the symptoms, correction of deformity, improve function, improve the patient's quality of life. Artificial joints has experienced more than a century, its design and material selection are materials engineers, biomechanics specialists and orthopedic surgeons ongoing efforts wisdom. Artificial joint development is closely related to the progress of materials science. With the material preparation methods and technology development, especially in recent years, with the continuous development of biomedical materials, engineering and technical personnel at home and abroad, and orthopedic surgeons are studying the use of new materials and manufacturing techniques designed various joint prosthesis to improve the material biocompatible, to prevent loosening of the prosthesis, and enhance the stability and flexibility of the prosthesis, improve the performance of artificial joints and prolong its using life. Knee arthroplasty as a means of treating disease of the knee have been increasingly attracted people's attention. Every year a large number of patients undergoing total knee replacement surgery, only the United States and Europe have done the surgery approximately 200,000 cases annual. This article describes in the total knee replacement surgery, pseudoarthrosis’s works, material requirements, material selection, design standards and so on.

Total Knee Koint Replacement (2)
Total knee joint replacement (TKR) arthroplasty is one kind of surgical technique which replaces all articulating degenerated natural surfaces of knee joints with aritificial materials, hence achieving relief of pain and improved joint mobility by creation of a new prosthetic joint. Although TKR is now a well establised orthopaetic technique involving the replacement of a growing number of knee joints, when compared with natural synovial joints, shorter life time is the most obvious defect of TKR due to the higer wear rates associated with artifical implant materials. In order to improve the performance, especially the contact stress of TKRs, not only the influence of clinical and design factors, but also the choice of counterpart materials should be considered.
This study introduced the knee joint replacement with emphasis on material selection and manufacturing process. The ideal TKR prostheses should be able to exhibit biocompatibility chemical combination, resist degratdation in the human body encironment, sustain the cyclic loading edured by joints. Hence, the physiology of human knee joint and working principles of TKR were described firstly. Then, the selection of artificial joint materials was discussed based on the functional requirements of knee joints. In the following sections, both the design criteria and manufacturingn process of the TKR were stated. Finally, the possible deveopment of this kind of TKR was discussed to some extent.

Biomaterials and Manufacturing Methods for Scaffold in Bone Tissue Engineering
In recent years, bone diseases (tumors or fracture) can cause bone defect which need substitutes such as bone grafts to replace the missing bone. Auto-grafts and allografts are two traditional bone grafts, however, auto-grafts are always insufficient and may cause an additional surgical pain to patient. Allografts often appear the rejected reaction created by foreign antigens in the graft materials. In order to overcome the limitation, the better way is to synthesize a replacement for nature bone which are biocompatible and biodegradable materials.
In this project, we discussed the present situation of the bone healing and compare different bone healing method. We analyze artificial bone’s working principle which is related to osteogenic progenitor cells, osteoinductive growth factors and osteoconductive scaffolds. The requirements to choose a proper scaffold for bone healing consist of four main factors which are materials’ surface properties, porosity and pore size, interconnectivity and mechanical properties. We discussed the possible errors (wrong selection of material and design errors) and the corresponding result.
Biocompatible and bioactive scaffolds might play a very critical role in regenerative medicine and tissue engineering. The function of scaffolds is to direct the growth of cells seeded within the porous structure of the scaffolds or of cells migrating from surrounding tissue. An adequate pore size and a uniformly distributed and interconnected pore structure to allow for easy distribution of cells throughout the scaffold structure are very important. The scaffold structure is directly related to fabrication methods. Over 20 methods such as Electro-spinning method, porogen-leaching methods and rapid prototyping have been proposed. Finally, we also analyzed the scaffolds’ market and future trending of artificial scaffolds for bone healing. To draw a conclusion, a novel biological scaffold which is biocompatible and bioactive for bone healing can meet the demand of market, and this kind of scaffold has broad space for development.

Design and Manufacturing of Surgical Instruments for the Treatment of Osteoporotic Fractures of the Spine
The International Osteoporosis Foundation estimates that more than 8.9 million elderly patients suffer from osteoporotic fractures each year, and that by 2050 rates for some fracture types will rise by 300% due to ageing demographics[1], [2]. While bone cement injection is a highly effective treatment method, problems remain; bone cement leakage into surrounding tissue can lead to dangerous complications. Leakage risks have slowed large-­‐scale adoption of bone cement for preventative care, and have held back the use of innovative bioactive bone cements that accelerate the rate of bone regrowth, an important feature for the elderly.[3] In response, our team at HKU has been working to develop a novel leak-­‐free minimally-­‐invasive cement injection system, featuring a thermo-sensitive polymer balloon that acts as a “smart barrier” to protect surrounding tissue in the patient’s body. A heating element accelerates the partially melting and/or dissolution of the thermo-sensitive/biodegradable material into the surrounding tissue once the cement has safely hardened. This paper provides an overview of the material, design and manufacturing considerations involved in the development of this novel medical device, in comparison to products currently available on the market such as vertebroplasty, kyphoplasty and vesselplasty systems from several international manufacturers.

DNA synthesis equipment
DNA synthesis is the natural or artificial creation of deoxyribonucleic acid (DNA) molecules. In nature, such molecules are created by all living cells through the process of DNA replication, with replication initiator proteins splitting the existing DNA of the cell and making a copy of each split strand, with the copied strands then being joined together with their template strand into a new DNA molecule. Various means also exist to artificially stimulate the replication of naturally occurring DNA, or to create artificial gene sequences. A polymerase chain reaction is a form of enzymatic DNA synthesis, using cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA. Artificial gene synthesis is the process of synthesizing agent in vitro without the need for initial template DNA samples. The main method is currently by oligonucleotide synthesis (also used for other applications) from digital genetic sequences and subsequent annealing of the resultant fragments.
In our project, our four group members are all curious about the DNA which is human gene basic construction part. We also want to know more about it, so we choose the device is DNA synthesis equipment.

Manufacturing of Customized Mechanostat Mandible Substitute
Aiming at restore the mandibular defect, this project introduced the design and manufacture method of customized mechanostat mandibular substitute for the immediate reconstruction as well as permanent restoration of mandibular defect. The patients’ CT images are gathered to design the contour of individualized titanium bone-grafting trays, which will be filled with autogenous iliac bone. Then Utah paradigm of skeletal physiology is applied in the functional design of mandible titanium substitute to achieve the mechanotransduction and the functional response of mandibular, say as mechanostat custom-made substitute. Before manufacturing, finite element analysis (FEA) model of this mandible substitute are established for environment simulation and structure optimization. According to Ashby chart, Titanium alloy is selected as the substitute’s material due to its high compatibility, suitable strength and low weight. The final structure of this substitute is first formed by lithography Apparatus into 3-D print plastic model. After that precision casting procedure is applied to further manufacture the plastic model into the final Ti6Al4V substitute. The customized mechanostat mandible titanium substitute shows a perfect performance in design and manufacture precision. Also the material choice and the application of mechanostat ensure its function of osteogenesis promotion, thus make it possible for permanent transplantation. This substitute combined reverse engineering technology and rapid prototyping technology which simplified the surgical procedure and achieved the transplantation successful rate. Furthermore the association of metal tray with autogenous bone graft has a potentially powerful advantage for mandibular defects restoration.

Vision correction by using Contact lens
According to the announcement by World Health Organization (WHO), till October 2013, 285 million people are estimated to be visually impaired worldwide: including 39 million are blind and 246 have low vision. Another fact is that about 90% of the world's visually impaired live in developing countries.
The theme of this report is one of the daily biomedical products - contact lenses. It is not uncommon for the use of vision correction. In order to recognize the marketing potential of contact lens industry, this report will include the marketing research of contact lenses, for example, a comparison of market share between contact lenses and glasses. Also, there will be description of different types of lens. Brief idea will be given for explanation. Further, we will discuss the functions and working principle of contact lenses, how the curvature of contact lenses correct the vision, the materials used for making contact lenses and the mechanical properties of such materials chosen.
Design of contact lenses is an important topic. Different criteria in designing contact lenses will be stated here, discussing how design factors affect the performance. For instance, the necessity of each design criteria, pros and cons of them. Moreover, during the design process, the possible design errors may exist. We will talk about them one by one. The manufacturing parts will focus on the methods and processes, the difficulties and limitations, and caution during manufacturing process. Finally, the future trend of contact lenses, such as new function and new technology, will be briefly introduced to prepare for the market planning.

Manufacturing of Coronary Stent (1)
Coronary heart disease (CHD) is a class of major diseases and the most common heart disease that is a threat to human health. Coronary heart disease is a kind of myocardial dysfunction and (or) organic disease caused by coronary artery stenosis and insufficiency. It is also called ischemic cardiomyopathy (IHD). A major cause (95% -99%) of coronary heart disease is coronary atherosclerosis. As the incidence of coronary heart disease continues to rise, the therapy of the CHD is more and more important nowadays. In the past, drug treatment and risk factors control are the main ways to improve survival of patients with coronary heart disease .With the birth and matures of the interventional coronary stent technology, percutaneous coronary intervention (PCI) become the most effective methods of treating coronary heart disease. Coronary stent is medical devices that commonly used in cardiac percutaneous intervention surgery. In the therapy, the coronary stent plays the most important role of clearing the arteries. So, the flexibility, anti-thrombosis, biocompatibility, expansion, supporting force, coverage, surface area, hydrodynamics and some another factors need to be consider in the design, material selection and ultimate manufacturing of this structure. This summary will briefly discuss the development of the coronary stent in the aspects that mentioned above.

Manufacturing of Cardiovascular Stent (2)
Nowadays, Coronary stent implantation is a rapidly evolving technology and has become a common practice in cardiovascular surgery in order to reduce stenosis or blockage of coronary arteries. For stents, generally, different metals have been used to manufacture them such as titanium, cobalt-chromium alloy, nitinol, 316L stainless steel, magnesium etc. And they are delivered through self-expansion or via balloon expansion, and the most commonly encountered designs include tubular mesh, slotted tubes or coils.
In this article, the cardiovascular disease was briefly introduced, and it mainly focused on the cardiovascular stent. The working principles of stent were also introduced. Based on it, the material requirements and selection method, products design criteria and possible design errors were discussed. Furthermore, two conventional manufacturing processes were described. Finally, a brief summary was given.
Looking in to the future, the area of stent manufacturing could have a bright future via novel processing.

Manufacturing of Intraocular Lens
An intraocular lens (IOL) is an artificial lens implanted in the eye to treat cataracts or myopia. It is a common surgery to replace the existing clouded over crystalline lens by IOLs for the elderly. IOLs were traditionally made of an inflexible material PMMA and has largely been superseded by the use of flexible materials like silicone and acrylic. In this project, we will go through the working principle, design criteria, fabrication, available features as well as other related aspects of IOLs.

Manufacturing of Locking Compression Plate(LCP)
Open reduction and internal fixation of fractures often involves metallic implants. They are commonly used in cases of trauma when the bone cannot be healed using external methods such as casting. The locking compression plate (LCP) combines the conventional screw hole, which uses non-locking screws, with a locking screw hole, which uses locking head screws. This provides the doctors more versatility in the application of the plate. LCP is used to fix the position of fractured bone, facilitating the healing process. It is already commercial available, and has been wildly used in bone fixation. In this report, in terms of material and main function, comparing between three types of plate, which are dynamic compression plate (DCP), locking plate (LP), and locking compression plate, will be introduced, and then working principle and basics of LCP will follow. Then the focus will be material requirement and material selection, considering mechanical property and biocompatibility. Ashby chart will be used as a method to analyze different material as plate candidate. Also the structure of plate plays critical role here. The most important design parameters are length, thickness, diameter of hole, and distance between holes. Furthermore, this report also addresses the possible design errors, manufacturing process, and future trend.

Manufacturing of Two Orthodontic Devices (Invisalign Orthodontic Aligner vs. Traditional Brace)
A good bite can enhance our oral, physical and even emotional health. Orthodontic technology has progressed to a level of efficiency and comfort recently. There are a lot of orthodontic treatments developed nowadays, such as metal braces, invisible braces, invisalign and so on. This report make a comparison between invisalign orthodontic aligner and traditional braces from six parts, including working principle, material requirements, material selection, design criteria, possible design errors and manufacturing. A choice of orthodontic method should be made under considering many factors. The possible future development of these two methods is also discussed. It is believe that the cost of invisalign will be reasonable and traditional braces can be invisible as well.

Manufacturing of Insulin Injection Pump
Diabetes mellitus is a very common disease with a symptom of high blood sugar concentration levels above normal range. Typically, it can be classified as three main types of diabetes, namely, type 1 diabetes mellitus, type 2 diabetes mellitus, and gestational diabetes mellitus. Untreated diabetes mellitus can lead to serious complications, such as heart disease, kidney disease, or even stroke. In this project, we mainly focused on type 1 diabetes mellitus caused by the dysfunction of pancreas and lack of enough insulin.
Treatment of type 1 diabetes mellitus requires strict regimens because pancreas loss the ability to synthesize insulin. Clinically, the insulin injection pump is commonly used to treat type 1 diabetes mellitus. The insulin injection pump is a portable, automatic and continuous delivering devices used for the type 1 diabetes patient in order to regulate the blood glucose levels in normal range. Basically, an insulin infusion device consists of several parts such as insulin reservoir, pumping components, infusion set and microchips. In this project, we paid more attention on the design and fabrication of shape memory alloy (SMA) wire based pumping structures, and nickel microneedles. Theoretical analysis and manufacturing methods were detailed for these two components. In addition, the working principle, material selection and design requirements were also covered briefly. Finally, further trends of insulin injection pumps were illustrated based on devices performance improvements.



Laboratory of Advanced Microfluidic Systems | Department of Mechanical and Biomedical Engineering | City University of Hong Kong
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