Design considerations for silicon sensors for use in catheters and guide wires

A growing field of application for micro-electromechanical systems is the medical field of minimally invasive interventions. These procedures use catheters and guide wires, inserted into the blood vessels, to reach places deep inside the body, without the need for open surgery. This reduces recovery time and discomfort to the patient, operating time and the risks involved with general anaesthetics. For proper diagnosis and monitoring treatment, more information is needed; silicon sensors for catheters and guide wires have been developed to obtain this information. As the accurate positioning of these instruments is problematic, it is desirable to combine several sensors on the same instrument to measure several parameters at the same location. However, there are many considerations in designing silicon sensors for this application, such as small size, low power consumption, biocompatibility of materials, patient safety, a limited number of connections, packaging, survivability of the sensor during use, etc. This paper will discuss the design considerations of micromachined (silicon) sensors and actuators for use in catheters and guide wires. As an example, a multiparameter blood sensor, measuring flow velocity, pressure and oxygen saturation, will be discussed.