A novel measurement system comprised of a portable
electronic instrument with an opto-chemical sensor for atmospheric oxygen
sensing is presented. Optical sensors based on luminescence quenching have been
thoroughly investigated in the search for sufficient sensitivity and high
stability.
The dye platinum octaethylporphyrin complex immobilised in a
polystyrene membrane was selected as an oxygen probe that was stabilised with
the heterocyclic amine DABCO, achieving in this way a mean drift of 0.01%
oxygen concentration per day. The portable instrument is based on a
microcontroller. Its main features are: a single optical oxygen sensor channel, lack
of optical filters, fully digital signal processing, autonomous operation with
computer communication capability for reprogramming and data saving and low
power consumption.
The use of a digital output photodetector makes it possible
to avoid analogue processing with the consequent circuitry saving and better
noise immunity. The measured parameter in the transduction process is quite
similar to the luminescence lifetime. The typical measurement range is from 0
to 30% oxygen and the response time is below 30 s for full range swing.
Typical instrument characteristics are temperature effect
correction, low drift and an accuracy of 0.5% in oxygen concentration for the
collective calibration curve. Better accuracy can be obtained with individual
sensor calibration. Dimensions and weight are 110 mm × 66 mm × 28 mm
and 95 g (without battery), respectively. Powering it with a standard
9 V PP3 battery for more than 10 days of operation is possible.
没有评论:
发表评论