Problem:

While developing the QFlow Perfusion Monitor we were asked to come up with a robust probe calibration architecture. The three calibration phases collect thermal information over a varying temperature range with each probe immersed in water, agar and glycerol baths. Both measured and calculated parameters are to be stored on a RAID 5 disk and individual probe results indexed within a SQL-Server database. The system diagram below shows the essential components.

Probes that pass all stages of testing ultimately go thru a 24-hour burn-in followed by programming of encrypted calibration parameters, system and security information. A Web-based application may be invoked to assess calibration lot progress. A sophisticated Probe Review application, shown below can query the database and numerically and graphically display a probe's thermal characteristics and coefficients and correlate these parameters across entire lots.

Shown below is one of three similar baths. Probes are loaded up 40 at a time and immersed into the precision bath. The operator screen allows test control, displays current probe status and system error conditions including hardware, disk or database malfunctions, in which case an email is sent to the operator on call. Probes that fail are flagged for further scrutiny by the quality assurance group

Results:

Probes must be certified, calibrated, initialized, and tracked thru the production pipeline and into the field. Proper calibration and efficient handling of the probes ensure the success of the instrument and also constitute a very substantial revenue stream.