We have experienced breakage of the lead wire in some of breathalyzers on our customers’ site. And we are considering to add a wire breakage function.  If you have any suggestions or recommendation for designing such wire break detection circuit or any other solutions, we would appreciate it.

Dart Sensors introduced the Electronic Verification Test for two electrode sensors in 2014. The full description is found on a Chinese patent application of that year.

In order to test a sensor for accuracy it is necessary to check it with a test gas. It would obviously be an advantage, in the absence of a test gas, to have a diagnostic test which can give information on whether the sensor is “live” and undamaged. This applies particularly in installations where the default result is zero, such as motor vehicle ignition interlock breathalyzers, as a safeguard against service failure.

The EVT imposes a current pulse on the sensor. Analysis of the system response to this process can verify either that the sensor is electrically and mechanically sound, or indicate both the presence and the type of fault, specifically:

  1. Sensor normal

  1. Sensor shorted out

  1. Sensor continuity broken: trace follows input pattern

  1. Sensor damaged by excessive temperature or mechanical disruption: peak enhanced owing to loss of capacitance.

DS customers can adopt the EVT free of charge. To obtain a copy of the patent application, get in contact with us.