Abstract: A blood pressure monitoring device includes a pressure sensing element mounted or a probe tip or in a catheter tip adapted for insertion into a patient's blood stream. The element includes a pressure transducer having a micromachined diaphragm which flexes in response to pressure changes. The flexes are converted by the transducer to electrical signals which pass back through the catheter to a display. The element and the catheter are conformally coated with a thin layer of parylene which insulates the device from the deleterious effects which blood components such as water and ions would otherwise have on various components of the device.