Development and characterization of a hydrogen peroxide sensor using catalase immobilized on a pyroelectric poly(vinylidene flouride) film

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Virginia Polytechnic Institute and State University

This dissertation describes the design, development and results of a simple, inexpensive, rugged, pyroelectric heat-of-reaction detector that can be made in many configurations. The measured heat of reaction results from the reaction of a substrate on an enzyme. The enzyme is immobilized in a flow channel with a pyroelectric polymer film, poly(vinylidene fluoride) or PVDF. The sample is introduced into the flow channel using flow injection analysis technology. The heat from the reaction causes the pyroelectric material to produce an electrical potential proportional to the change in temperature which, in turn, is proportional to the substrate concentration. This potential is amplified and recorded.

A differential instrument amplifier produces a difference signal from a sample and reference PVDF film. This removes noise caused by stray electromagnetic radiation and piezoelectric pressure responses.

A conventional Flow Injection Analysis unit was employed. The FIA flow rate was four ml/min and the time from injection to peak maximum was less than three seconds, with a return to baseline of less than thirty seconds. This gives a quick analysis time and a reasonable number of analyses per unit time. Data interpretation is straight forward, peak height is proportional to the concentration.

A 70 μl sample gives a good response. Larger samples do not improve the signal. The system showed minimum detectable number of moles that is comparable to other methods, 7 x 10⁻⁸ moles.

The detector showed good response for more than two orders of magnitude. The results show excellent correlation to the modeled system of heat trans+er through the PVDF sensor.