In this report, we detailed the design and fabrication of a nitric oxide (NO) sensor for cell culture measurements. As an example, we considered NO sensor design for hypoxic cell culture applications (cells which can proliferate at less than 4% oxygen concentration). Primarily, a set of 2D, steady state, reaction coupled diffusion simulation is performed. The simulation results suggest the optimal design of NO sensor array for NO hypoxic cell culture applications. It also deduces the current corresponding to pericellular NO concentration. From the design interpretations, we fabricated thin-film, planar, nitric oxide sensor array (electrode dia. 50 ??m) for hypoxic cell cultures which is integrated at the bottom of the cell culture flask to form sensing cell culture flask (SCCF) for NO. We also presented the long-term measurement (upto 18 hrs) of MCF-7 hypoxic breast cancer cells which shows a linear increase in current with respect to time.