A prototype Polydimethylsiloxane (PDMS) based microbioreactor integrated with a photodiode detector for monitoring intracellular green fluorescent protein ultraviolet (GFPUV) expression is described. The developed system is compact, simple and inexpensive thus making it ideal for an economical on chip detection of intracellular GFP and other biological applications. The detection limit for cell free GFPUV was found to be 4.8 ×10
M while for Fluorescein isothiocyanate (FITC) was found to be 1.2 ×10
M. The performance of the photodiode detector was benchmarked with a CCD spectrophotometer and results showed favorable comparison. This study demonstrates the quest to develop integrated microsystems that can be used to monitor cellular dynamics in real time.