Properties of PT/P(VDF-TrFE) pyroelectric sensor based on plastic film substrate

Nanosized lead titanate (PT) powder obtained by a sol-gel method was homogeneously mixed with vinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] to form a nanocomposite with 0.12 volume fraction of PT. The PT/P(VDF-TrFE) nanocomposite film was used as the sensing element of pyroelectric sensors, whose detectivity was about 20% higher than that of sensors using pure P(VDF-TrFE). A 35 nm indium tin oxide (ITO) film was deposited as the bottom electrode on a poly(ethylene terephthalate) (PET) plastic film substrate, and a Ni-Cr film was deposited as the top electrode and absorption layer. The PET plastic substrate could effectively decrease the thermal conductivity of the element, consequently the thermal fluctuation noise of the pyroelectric element was decreased significantly and the voltage responsivity was increased. The experimental results indicated that the specific detectivity of PT/P(VDF-TrFE) pyroelectric sensors based on PET film substrate reached 1.3E7 cmHz 1/2 W-1, which is more than one order of magnitude higher than that the sensor fabricated under the same condition on bulk silicon. © 2002 Taylor & Francis.