ABSTRACT
The ideal noninvasive way to measure the pressure is from outside the body. The catheter is filled with fluid to transmit internal pressure in the body to the external sensor. Due to the effect of gravity on the fluid, the sensor should be placed at the same level as the catheter tip. Most pressure sensors for direct measurement have an elastic diaphragm. Many strain-gage pressure sensors are available, such as PIOEZ. For the capacitance pressure sensor, there are no mechanical contact, friction or hysteresis errors in the measurement. But a catheter-tip pressure sensor is difficult to calibrate and is relatively expensive for disposable use. The strain-gage catheter-tip pressure sensor is used in clinical applications. The pressure sensor is attached to the back side of the diaphragm to measure the deformation of the silicone rubber diaphragm. A bundle of wires connects the sensor and other electric equipment through the vent tube.
