Microfluidic and Holographic Microscopy Integrated Optoelectronic Tweezers For Single-cell Applications
Optoelectronic tweezers (OET), combining the advantages of optical and dielectrophoretic (DEP) manipulation, has been widely used in laboratories around the world. Despite being a useful platform for single-cell manipulation, OET still suffers from two limitations, the difficulty of being integrated with microfluidic components and the lack of large-area real-time detection function. The two issues restrain OET from complicated single-cell analysis and large-area automated manipulation. To integrate the PDMS-based microfluidic components with OET, two techniques are purposed in this research, SWNT-embedded electrodes and 3D PDMS membranes. The first technique uses SWNT thin films as transparent and conductive electrodes for OET inside multilayer PDMS channels. 3D microfluidic technique makes PDMS membranes to be a multilayer network between two rigid OET substrates. Based on these two new fabrication methods, novel microfluidic OET platforms have been developed to enable single or multiple cell manipulation and to accomplish multi-steps tasks. Therefore, off-chip and on-chip single-cell RT-qPCR are achieved on these two platforms respectively.
To address the issue of large-area real-time detection, a new technology, holographic on-chip imaging microscopy, is employed. This integrated platform has optical detection area equal to the size of an optoelectronic sensor array. Recording holographic images or digital reconstruction images, the automated image analysis in the system can keep the real-time positions of thousands of objects in field of view. Based on the real-time position information, the system simultaneously transports the target objects to the desired destinations. Particles or cells can be patterned or sorted on the platform which enabling simultaneous automated imaging, image analysis, real-time position feedback and interactive manipulation of thousands of micro-objects over an area of 240 mm2.