VFR resistors simulate and calibrate thermistor measurements

17th December 2013

Nat Bowers

0 0

Vishay Precision Group release a new video demonstrating Bulk Metal Foil precision resistors used to simulate and calibrate temperature measurements in hypersensitive thermistor-based system circuits which are capable of detecting temperature changes of less than 0.01°C. The video uses a hypothetical case study of a medical researcher working on a project to detect blockages in the human cardiovascular system, watch it below.

The test system shown in the video makes use of thermistors coupled to an extremely sensitive and accurate resistance bridge. This carefully measures the temperature of a simulated circulatory system. The researcher looks for the most minute fluctuations in temperature as the circulatory system's flow is manually disrupted. In real world applications, these disruptions could be blockages in an artery or vein.

While thermistors can be used to make extremely sensitive temperature measurements, this sensitivity can also be their biggest drawback. Without the proper instrumentation, self-heating effects and non-linearity can make it extremely difficult to use accurately. The VFR Bulk Metal Foil resistors are particularly suitable for calibrating and maintaining the accuracy of extremely sensitive thermistor-based temperature measurement instruments used in the medical field.

Featuring TCR of less than 0.5ppm/°C and long-term stability of a few ppm per year, VFR resistors can exactly duplicate the ohmic value of a thermistor to six digits with tolerances as tight as ±0.001% at the desired temperature. The sensitivity and accuracy in this simulated system can only be achieved by using VFR resistors as both the reference and calibration resistors in the precision bridge circuit. By substituting them into the bridge circuit in place of the thermistor, the circuit can be balanced and calibrated to extremely sensitive and accurate levels.