A multi-sensor silicon needle including two ion-sensitive field effect transistor (ISFET) sensors, a platinum pseudo-reference electrode (Pt) and a temperature sensor has been fabricated by using a CMOS-compatible technology and silicon micromachining. This paper presents a summary of the fabrication process and results of the device characterisation. The feasibility of the fabrication technology has been demonstrated and all devices have operated satisfactorily, with a response showing good sensitivity and linearity. The multi-sensor has been developed for the detection of myocardial ischemia during cardiac surgery.