Patent ID: 7116421

Claim:
An apparatus for detecting hydrogen gas comprising: a radiation source for generating at least two optical signals of about the same modulation frequency; a sensor head, comprising a pyroelectric film, the pyroelectric film including a first side coated with a hydrogen-sensitive metallic substance and a second side with a hydrogen insensitive metallic substance; said sensor head, comprising a pyroelectric film with a hydrogen-sensitive side, which is further overcoated with a protective coating preventing the said hydrogen sensitive metallic substance from becoming poisoned due to prolonged exposure to ambient pollutants; a remote optical signal transmission element for delivering from the radiation source an optical signal to the first side and an optical signal to the second side, thereby generating an essentially zero voltage or signal base line suppression across the two sides in the absence of hydrogen gas and a non-zero differential voltage in the presence of hydrogen gas; circuit element to generate the modulated optical excitation and detect the modulated generated differential signal; circuit element electronically connected to the two sides for monitoring the modulated voltage and demodulating said differential signals; and outputting said demodulated differential signals and storing said demodulated differential signals or displaying said demodulated differential signals.