System and method for in vivo calibration of a sensor

A method of calibrating a sensor system having a first sensor that moves within a range when sensing a physiological parameter, the sensor system also having a processing system that monitors the position of the first sensor and provides an output signal representative of the physiological parameter based on the monitored position of the first sensor, the method of calibrating comprising the steps of:

• locating a stop device to restrict the first sensor to a known position outside the sensing movement range when the sensor is engaged with the stop device;
• selectively applying force to the first sensor to move it into contact with the stop device;
• measuring the force applied by the force generator and providing a measured force signal representative of the force applied by the force generator to move the first sensor into contact with the stop device;
• storing in a memory a reference force used to move the first sensor from a selected position at which the first sensor was subjected to a first force to the stop device;
• controlling the force generator to apply force to the first sensor to move it from an unknown position resulting from an unknown force acting upon the first sensor to the stop device;
• retrieving the reference force from the memory;
• and
• determining the value of the unknown force based on comparing the reference force to the measured force.

A calibration system for calibrating a sensor system having a first sensor that moves within a range when sensing a physiological pressure and a second sensor that determines the position of the first sensor, the second sensor providing a position signal representative of the position of the first sensor, the sensor system also having a processing system that monitors the position signal and provides an output signal representative of the physiological pressure based on the monitored position of the first sensor, wherein the first sensor movement range comprises a maximum position at which the first sensor would be located should the physiological parameter reach a maximum predetermined level, the calibration system comprising:

• a stop device located so as to restrict the first sensor to a known position outside the sensing movement range when the sensor is engaged with the stop device, the stop device being located beyond the maximum position of the first sensor;
• a controllable pressure generator that selectively applies pressure to the first sensor to move it into contact with the stop device;
• a pressure gauge that measures the pressure applied by the pressure generator and provides a measured pressure signal representative of the pressure applied by the pressure generator to move the first sensor into contact with the stop device;
• and
• a memory having stored therein a reference pressure used to move the first sensor from a selected position at which the first sensor was subjected to a first pressure to the stop device;
• wherein the processing system controls the pressure generator to apply pressure to the first sensor to move it from an unknown position resulting from an unknown pressure acting upon the first sensor to the stop device, receives the measured pressure signal from the pressure gauge, retrieves the reference pressure, and determines the value of the unknown pressure based on comparing the reference pressure to the measured pressure.

A sensor mounting system for mounting a first sensor that moves within a range when sensing a physiological parameter and a second sensor that determines the position of the first sensor, the responses of both the first and second sensors being dependent upon their positioning at a particular location in respect to the parameter to be sensed, the mounting system comprising:

• a first housing within which the first sensor is mounted;
• a second housing within which a stop device located so as to restrict the first sensor to a known position outside its sensing movement range when the sensor is engaged with the stop device is mounted;
• wherein the first housing and second housing are movable in relation to each other along the direction of movement of the first sensor to provide for the sensing movement range of the first sensor and to locate the stop surface outside that movement range so that the first sensor is located at the particular position;
• wherein the second and first housings are movable in relation to the second sensor so that the first sensor is locatable at the particular position in respect to the first sensor.

A method of mounting a plurality of sensors of a sensor system in relation to each other, the plurality comprising a first sensor that moves within a range when sensing a physiological parameter and a second sensor that determines the position of the first sensor, the responses of both the first and second sensors being dependent upon their positioning at a particular location in respect to the parameter to be sensed, the method comprising the steps of:

• mounting the first sensor in a first housing;
• mounting in a second housing a stop device located so as to restrict the first sensor to a known position outside its sensing movement range when the sensor is engaged with the stop device;
• moving the first housing and second housing in relation to each other along the direction of movement of the first sensor to provide for the sensing movement range of the first sensor and locating the stop surface outside that movement range so that the first sensor is located at the particular position;
• and
• moving the second and first housings in relation to the second sensor so that the first sensor is locatable at the particular position in respect to the first sensor.