Quantitative Phase Technology Using Silicon Designed to Visualize Cellular Processes

In a study published October 2, 2013, in Nature’s online journal Scientific Reports, the investigators reported that it overcame past limitations on quantitative microscopy through an opaque media by working with a new combination of near infrared light and a technique called quantitative phase imaging. The technology is approximately 10-years old and uses shifts in phases of light, not staining techniques, to aid specimen imaging—warranting the term “label-free.”

“To the best of our knowledge, this is the first demonstration of quantitative phase imaging of cellular structure and function in silicon environment,” said Assistant Professor of physics Dr. Samarendra Mohanty, head of the biophysics and physiology laboratory at University of Texas (UT) at Arlington (USA), and corresponding author of the article.

The UT at Arlington and Massachusetts Institute of Technology (MIT; Cambridge, MA, USA) group of scientists was able to study specimens through a silicon wafer in two cases. In one, they achieved full-field imaging of the features of red blood cells to nanometer thickness accuracy. They observed, in another specimen, the dynamic variation of human embryonic kidney cells in response to variations in salt concentration. Dr. Mohanty believes that his group’s current research on near-infrared quantitative-phase imaging can lead to noninvasive, label-free monitoring of neuronal activities.

“Silicon-based microdevices known as labs-on-a-chip are revolutionizing high throughput analysis of cells and molecules for disease diagnosis and screening of drug effects. However, very little progress has been made in the optical characterization of samples in these systems,” said Dr. Bipin Joshi, a recent graduate and lead author of the study. “The technology we’ve developed is well-suited to meet this need.”

Dr. Barman, now an assistant professor at Johns Hopkins University (Baltimore, MD, USA), stated that this study is an excellent example of the type of research he envisages doing, projects driven by needs of the biomedical community and continually pushing the edge of biophotonic technology. “We envision that this significantly expands the visualization possible in silicon based microelectronic and micromechanical devices,” he said.

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University of Texas at Arlington
Massachusetts Institute of Technology