Current technology of Organ-on-Chips allows investigation of human cells outside the body including a microfluidic medium flow. Control of oxygen in this microfluidic flow is required to mimic the situation as in the human liver (physiological) or to create temporary low oxygen concentrations (hypoxia). In this research, a gas exchanger module is designed for liver-on-a-chip cell experiments at the Erasmus MC. Based on prototype tests and COMSOL simulations, the gas exchanger module is designed and integrated with a commercial Micronit microfluidic channel. The functioning of the fabricated gas exchanger is validated by measuring an oxygen gradient as well as performing oxygen consumption measurements on a liver cell layer.