Thermally stimulated discharge of electrets

A review of insect antennae sensilla is given and the dimensions and forms of the sensilla are related to dielectric waveguide theory The design criteria for antennae include dielectric constant measurements, shapes, molecular emitters (molecules), length/wavelength, thin layer outer covering of sensilla, and the electret properties of antennae Sensilla are described in terms of open resonator-waveguide theory, and the length and diameter of various species of insects are fitted to the 2 wavelength criteria of open resonator design The importance of tapering the open resonator sensilla for good frequency “fit” is emphasized Characteristics of molecules of insect attractants are described in terms of their luminescent and fluorescent properties The surface textures of various types of insect sensilla are related to the form characteristics of efficient open resonator systems Surface textures found on insect sensilla include smooth, corrugated, helical, equiangular, terraced, and furrowed The attraction of molecules to sensilla pores is demonstrated and explained in terms of the electret properties of the outer wax layer of the epicuticle The various shapes of the sensilla are classified into 15 categories, all of which except No 15 (corn ear configuration) can be found described and utilized by man-made communication systems in the microwave region A table is given of the vibration frequency range of various orders of insects, and the frequencies are related to the modulation content of infrared emissions from host plant and pheromone attractants The Johnston's organ is considered by the author as a piezoelectric feedback (pressure) transducer utilized by the insect to set and hold the proper modulation frequency Insect grooming is related to the electret properties of the sensilla and the rubbing of sensilla to the maserlike emissions from insect host plant and pheromone attractants Based on the 7 criteria of length and diameter of sensilla, dielectric constant, sensilla electret properties, apertures in sensilla, surface sculpturing, form, and (array) arrangements of sensilla, and also on the vibration frequency and grooming of the cabbage looper moth, log-periodic infrared emissions were predicted from the pheromone As predicted, log-periodic maserlike frequencies were detected in the 17 and 26-μm infrared regions They emit log-periodic with time over a half-hour period At a wind speed of 0·5 M per minute the pheromone emits long wavelengths close to the female and short wavelengths further from the female This is termed “concentration tuning” and operates as a proximity frequency indicator to the male flying the maserlike beam of scent In the opinion of the author, the evolutionary selection of species has involved divergent drift in the form of the antenna sensilla concurrent with the selective pressure of gradually changing molecular emissions The emission shifts conceivably were due to the changing infrared environment over the eons

Insect antennae with special reference to the mechanism of scent detection and the evolution of the sensilla

Physical principles of electrets

Through detailed investigations of the modulation frequency response of pyroelectric detectors, nonuniform polarizations have been shown to exist in polyvinylfluoride and polyvinylidene fluoride plastics. The nonuniform polarization is also confirmed by measurements using multilayer structures. The direction and magnitude of the gradients in polarization are dependent on the magnitude and polarity of the poling voltage. The gradients in the polarization for PVF and PVF2 are opposite in direction. Using structures that allow for poling to 2 × 106 V/cm uniform polarizations, the highest responsivities and improved frequency responses were obtained.

The Polarization of PVF and PVF2 Pyroelectrics

IT has already been established in this laboratory that the mechanism accounting for the long range transmission and preservation of structural information by amorphous inter-facial layers prepared on top of crystals is the thermoelectret1 or photoelectret2 mechanism. The charged elements of the real structure of the surfaces of crystal substrates produce in these layers a certain electret structure which copies the electrical relief of the underlying substrate surface. This electret structure which is frozen in interfacial layers is so stable that it persists even after the layers are detached from the crystals; the interfacial layers turn out to be electrical copies of the surfaces of solids, in other words.

V. M. Fridkin

Papers

Photoelectrets and the electrophotographic process