CMOS contact imager for monitoring cultured cells

There is a growing interest in developing low cost, low power, highly integrated biosensor systems to characterize individual cells for applications such as cell analysis, drug development, environmental monitoring, and medicine. In such micro-systems, it is desirable to track individual cells in real time in order to steer cells using on-chip micro-actuators or monitor the movement of motile cells. To address this requirement, we are developing an embedded optical image sensor, called a contact imager, for imaging of a biological specimen directly coupled to the chip surface. The designed CMOS image sensor comprises an array of active pixel sensors (APS), logic and control signal generation, and readout circuits. The pixel layout has a pitch of 8.4 μm (24 λ). The design was fabricated in a commercially available 0.5 μm CMOS technology. The imager was first characterized on the bench as a normal CMOS image sensor, and then as a contact imager with microbeads (16 μm) placed directly on the chip surface. After further packaging with bio-compatible material, the chip was tested with cells cultured directly on the chip surface. Test results confirm successful detection of both beads and cells.