The present disclosure relates to a microfluidic device for measuring one or more parameters in a fluid sample, which includes a sample microfluidic channel disposed on a solid substrate, a reagent microfluidic channel disposed on a solid substrate, a mixing microfluidic channel disposed on a solid substrate, and an optical reading window located downstream of the mixing microfluidic channel, through which a response indicative of the parameter(s) change can be measured optically. The present disclosure also relates to an apparatus for measuring one or more parameters in a fluid sample which includes the microfluidic device as well as a method for measuring one or more parameters in a fluid sample through the device or the apparatus.