Super-resolution: developing low-cost technology for biophotonic research
Developing low-cost and effective solutions to important problems has always been scientists’ biggest hope. Dr Antony Chi Shing Chan (Croucher Fellowship 2016) was able to minimize biophotonics research cost. He is currently a postdoctoral researcher in the Engineering & Applied Science Division at California Institute of Technology (Caltech) in the United States.
Chan’s interest in biophotonics began at the University of Hong Kong, where he worked as a graduate student at Professor Edmund Lam’s and Dr Kevin Tsia’s laboratories. Back then, Tsia developed a new camera technique called serial time-encoded amplified microscopy (STEAM). Known as the world’s fastest camera by Nature News when it was developed in 2009, the camera was able to capture 6 million images per second and was considered a potential equipment to study dynamic events such as combustion, laser surgery, chemical dynamics in living cells, microfluidics, and MEMS.
However, a major challenge in applying this technology to academic and industrial research, especially in Asia, was the need of a specialised oscilloscope with high bandwidth to read large amount of image quickly. Such high-speed oscilloscope can only be purchased from the United States and requires a special security clearance. “Procuring such equipment took months of advance planning. And when there is an issue with the equipment, we have to ship the equipment back to the United States for repair, which limits the applicability of the technology to biological and industrial research significantly, especially in East Asia.”
Seeing this challenge as an opportunity, Chan decided to develop an alternative approach to STEAM using cheaper and more accessible components. After exploring different options and discussing with researchers from other fields, he found that a medium-grade digitizer called ROACH could replace the expensive oscilloscope. Compared to the original oscilloscope, it takes only one-fourth of the data readout speed at the expense of lowering image resolution by half.
Despite the shortfall, Chan cleverly modified the STEAM system to better utilise memory in the hardware, allowing continuous image of 10,000 cells per shot, as compared to 20 cells with the previous method. Together with a computational technique called pixel super-resolution, the new method is capable of high-volume cellular screening to allow meaningful clinical diagnosis at a lower cost.
With support from the Croucher Foundation, Chan is currently working as a postdoctoral researcher at Professor Changhuei Yang’s laboratory at Caltech. Following his passion in making technology accessible and affordable, his new research project focuses on converting a relatively inexpensive conventional microscope to a billion-pixel resolution imaging system that could significantly advance biomedical and pathology research.
Conventional microscope is constrained by the physical limitation of optics and there is always a tradeoff between resolution and field of view – a high-power objective results in a small coverage area but higher resolution, whereas a low-power objective gives large coverage area but lower resolution.
Chan’s current research attempts to overcome the tradeoff between coverage and resolution with a low-cost solution. By using a $200 LED array and clever imaging algorithm, termed Fourier psychographic microscopy, series of obliquely-illuminated, low-resolution images can be stitched together to form a high resolution image with a coverage as large as a petri dish, which enables a wide range of applications in digital pathology and pharmaceutical research. Because of this, Chan is also actively collaborating with pharmaceutical companies to apply his research to clinical discoveries. “I am deeply grateful for Croucher Foundation’s support to my research at Caltech, which gives me the opportunity to work with top researchers in the field and opens my eyes to applying cutting-edge technology to the industrial research.”
Upon self-reflection and considering where his future will lie, Chan remembers a book he read, October Sky, which describes the journey of a young boy from a coal-town in pursuing his dream, and, against all odds, persevered to become a rocket scientist at NASA. Inspired by this story, Chan is confident that with hard work and persistent, he can also do great things to scientific research and more broadly, humanity.
Dr Antony C.S. Chan received the B. Eng. (1st class honour) degree in Medical Engineering from the University of Hong Kong in 2012 and a PhD from the University of Hong Kong for the work on optical high-throughput microscopy with a single pixel detector. His research interests include real-time cellular microscopy and computational image restoration for biomedical application. He was selected to participate the Siegman International School on Lasers in 2014. He also received the Newport Spectra-Physics Research Excellence Travel Award in the Photonics West conference in 2016.
To view Dr Chan’s Croucher profile, please click here.