An integrated optical stretcher and microfluidic system for biological physics

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Photons of light carry momentum and exert forces when they impinge matter. In the macroscopic world, these forces are relatively small and go unnoticed. In the microscopic world, light momentum can have significant mechanical consequences. Taking advantage of this, optical traps have been developed in which focussed light can be used to trap dielectric particles in a fluid medium. A recent development has extended the use of light from simply trapping an object, to being able to mechanically stretch it. The so called "Optical Stretcher" has become an important and easily implemented tool in which to trap single living cells while being able to mechanically stretch them. Unlike a traditional optical trap which requires extensive optical and electronic components, the optical stretcher relies simply on two unfocussed beams of light being aligned in an opposed manner. When a cell intersects with these two beams the balance of forces will act to trap the cell because the net force acting on it will be zero. However, the forces acting on the cell membrane opposite from the point of the light source will be greater than zero which results in a mechanical stretch. In combination with optical microscopy one is now able to perform mechanical measurements of cells, detect various disease states based on these measurements and image mechanical deformation in a high-throughput manner. In this proposal we are seeking funds to build an integrated optical stretcher and microfluidic system not only to trap and mechanically stretch cells, but also to simultaneously change their physiological environment via microfluidic exchange, high throughput mechanical analysis, biophysical sensing, and downstream cell sorting. Such a system is not commercially available and will be the first of its kind in Canada and internationally. This will provide a unique opportunity for HQP training in the interdisciplinary science of biological physics, gaining experience in instrumentation, microscopy, optics and cell/molecular biology. The requested system will also enable the investigation of medically relevant biophysical properties of cells with applications ranging from enhancing our understanding of cell biology to developing high-throughput sensing and screening technologies.