Associate Memberships: Department of Urological Sciences, Vancouver Prostate Center
B.A.Sc (UBC), M.Sc. (MIT Media Laboratory), Ph.D. (MIT Electrical Engineering)
ph: (604) 827-4703
fx: (604) 822-2403
lab website: Multi-Scale Design Laboratory
- Microfluidics and BioMEMS
- Biomedical Device Design
- Biomechanics of Cells
- Technologies for Global Health
- Bio-mimetic Design
Current Research Work
Microfluidic Cell Sorting by Mechanical Deformability
Fast, efficient separation of specific types of cells from heterogeneous mixtures is of fundamental importance in many areas of biological research and medical practice. Present separation techniques are limited by selectivity, throughput, as well as the need for chemical labeling. Microfluidics and microfabrication technologies present unique opportunities to create geometries and mechanisms at the size-scale of individual cells to enable new separation modalities. We are currently developing new mechanisms to actively deform cells in flow in order to separate cells by their mechanical properties.
Low-cost Malaria Detection Device
Malaria is one of the greatest challenges facing human health today. Globally, there are between 200 to 500 million cases of malaria per year resulting in 1 million deaths, the vast majority of which are young children. Accurate, sensitive, and cost-effective diagnostic tests are central to the global campaign to control and eradicate malaria. Inaccurate diagnosis not only results in patient mortality and morbidity, but also leads to ineffective use of treatment resources and could potentially accelerate the emergence of drug-resistant strains.
Malaria is caused by a protozoan parasite that invades human red blood cells. Currently, the gold standard detection method is the microscopic examination of Giemsa-stained blood smears to determine the density of infected red blood cells. This detection technique is sensitive and quantitative, but requires expertise and equipment often not available in low-resource regions. Rapid diagnostic tests based on immune-capture of antigens specific to the malaria parasite are a promising low-cost alternative. However, these tests are not as sensitive as microscopy, they do not provide a quantitative measure of parasite density, and they can produce a positive result even when parasites are no longer viable. We are developing a low-cost and portable device for detection of malaria infection that can quantitatively determine parasite density and discriminate viable and non-viable parasites. Such a device could be used to direct treatment until the clearance of all viable parasites, as well as to evaluate the effectiveness of new drugs and vaccines in clinical trials.
Magnetic Endotracheal Tube Sensor
The endotreacheal tube is ubiquitous in hospital procedures, used to keep patient airways open during mechanical ventilation. Placing the tube at the correct location in the throat requires a high level of skill and training, and it is secured in place with a variety of tape and/or tie systems. Unplanned loss of ETTs is a catastrophic problem that can result in patient mortality or morbidity. Often times, these problems occur simply because the expertise required for immediate replacement of ETTs cannot be maintained at the bedside of every patient. The position of the tube is currently monitored by periodic chest X-rays, which even if taken daily are too infrequent monitors of ETT position, and are undesirable because of unnecessary radiation exposure. We have previously demonstrated the potential to locate the position of an ETT using an array of magnetic field sensors as shown in the figures below. We are developing a low-cost disposable system that could continuously monitor ETT position to warn clinicians of tube displacement so that corrective action could be taken to prevent tube-loss.
- H. Ma, J.H. Lang, A.H. Slocum, Calibration-free Measurement of Liquid Permittivity and Conductivity using Electrochemical Impedance Test Cell with Servomechanically Adjustable Cell Constant, IEEE Sensors. (Accepted)
- O.T. Ogunnika, M. Scharfstein, R.C. Cooper, H. Ma, J.L. Dawson, S.B. Rutkove, A Handheld Electrical Impedance Myography Probe for the Assessment of Neuromuscular Disease, in Proceedings of the IEEE Engineering in Medicine and Biology Conference, Vancouver, Canada, 2008.
- W. Wichakool, B.J. Pierquet, K.V. Durand, B.B. Hsu, R. Sheridan, H. Ma, Magnetic Endotracheal Tubes Imaging Device, in Proceedings of the IEEE Engineering in Medicine and Biology Conference, Vancouver, Canada, 2008.
- F.C. Chen, H. Wu, P.L. Hsu, B.A. Stronger, R. Sheridan, H. Ma, SmartPad: A Wireless, Adhesive-Electrode-Free, Autonomous ECG System, in Proceedings of the IEEE Engineering in Medicine and Biology Conference, Vancouver, Canada, 2008.
- H. Knight, J. Lee, H. Ma, Chair Alarm for Patient Fall Prevention based on Gesture Recognition and Interactivity, in Proceedings of the IEEE Engineering in Medicine and Biology Conference, Vancouver, Canada, 2008.
- H. Ma, J.H. Lang, A.H. Slocum, Permittivity Measurements using Adjustable Microscale Electrode Gaps between mm-Sized Spherical Electrodes, Review of Scientific Instruments, Vol. 79, No. 3, p. 035105, 2008.