A novel one-step microfabrication process of SU-8 films for the development of inexpensive light-weight and small size optical glucose micro-biosensors is proposed. Experimental work was carried out in order to investigate whether SU-8 photoresists, which are polymers widely used in MEMS applications, can be utilised as immobilisation matrices for the simultaneous encapsulation of glucose oxidase and an oxygen-sensitive fluorescent indicator. The immobilisation of the enzyme, the encapsulation of the indicator and the patterning of the custom-made SU-8 take place simultaneously, thus simplifying the microfabrication process.