An Integrated imaging sensor for rare cell detection applications

Altıner, Çağlar
Cell detection using image sensors is a novel and promising technique that can be used for diagnostic applications in medicine. For this purpose, cell detection studies with shadowing method are performed with yeast cells (Saccharomyces cerevisiae) using an 32×32 complementary metal oxide semiconductor (CMOS) image sensor that is sensitive to optical illumination. Cells that are placed zero distance from the sensor surface are detected using the image sensor which is illuminated with four fixed leds to maintain fixed illumination levels in each test. Cells are transferred to the sensor surface with drying the medium they are in, which is phosphate buffered saline (PBS) solution. Yeast cells that are zero distance from the surface are detected with a detection rate of 72%. Then, MCF-7 (breast cancer) cells are detected with the same sensor when the PBS solution is about to dry. To investigate the detection capability of the sensor while the cells are in the PBS solution, the sensor surface is coated with gold in order to immobilize the surface with antibodies. With immobilizing antibodies, cells are thought to be bound to the surface achieving zero distance to the sensor surface. After coating gold, antibodies are immobilized, and same tests are done with MCF-7 cells. In the PBS solution, no sufficient results are obtained with the shadowing technique, but sufficient results are obtained when the solution is about to dry. After achieving cell detection with the image sensor, a similar but large format image sensor is designed. The designed CMOS image sensor has 160×128 pixel array with 15µm pitch. The pixel readout allows capacitive and optical detection. Thus, both DNA and cell detection are possible with this image sensor. The rolling line shutter mode is added for reducing further leakage at pixel readout. Addressing can be done which means specific array points can be investigated, and also array format can be changed for different size cells. The frame rate of the sensor can be adjusted allowing the detection of the fast moving cell samples. All the digital inputs of the sensor can be adjusted manually for the sake of flexibility. A large number of cells can be detected with using this image sensor due to its large format.
Citation Formats
Ç. Altıner, “An Integrated imaging sensor for rare cell detection applications,” M.S. - Master of Science, Middle East Technical University, 2012.