Recently, micro fluidic devices have received considerable attention because of the many potential applications in medicine and environmental monitoring. In such systems, cells and particles suspended in fluids can be manipulated for analysis. Micro fluidic systems are projected to develop more complex functions as they integrate electronic/optoelectronic sensors that could monitor the activity within micro channels. This paper presents research work on modeling and simulation of a CMOS Active Pixel Sensor providing some basis for the future integration with micro fluidic devices. Computer simulations are carried out demonstrating the functionality of each stage of the sensor and a small pixel array is modeled and simulated incorporating the addressing and reset signals. Results illustrate how the performance of the CMOS active pixel sensor can be adjusted to meet the specifications for scientific applications. © 2011 IEEE.