Apparatus and associated methods relate to a functional self-test, including (1) generation of an excitation signal, (2) applying the excitation signal to a unit under test (UUT), the excitation signal including a cyclical signal for a first interval and substantially zero signal for a second interval, (3) determining frequency content of a UUT response signal, and (4) generating a fail result in response to the frequency content below a predetermined threshold. In an illustrative example, the UUT may be a piezoelectric element (PE). The UUT response signal may be processed by a filter, for example. A portion of the filtered UUT response signal, responding to the second interval of the excitation signal, may be analyzed by a fast Fourier transform module (FFTm), for example. In various implementations, the functional self-test may advantageously determine the health of a piezoelectric gas sensing element, periodically, in a field-deployed implementation.

Apparatus and associated methods relate to a functional self-test, including (1) generation of an excitation signal, (2) applying the excitation signal to a unit under test (UUT), the excitation signal including a cyclical signal for a first interval and substantially zero signal for a second interval, (3) determining frequency content of a UUT response signal, and (4) generating a fail result in response to the frequency content below a predetermined threshold. In an illustrative example, the UUT may be a piezoelectric element (PE). The UUT response signal may be processed by a filter, for example. A portion of the filtered UUT response signal, responding to the second interval of the excitation signal, may be analyzed by a fast Fourier transform module (FFTm), for example. In various implementations, the functional self-test may advantageously determine the health of a piezoelectric gas sensing element, periodically, in a field-deployed implementation.

The present invention includes scalable and cost-effective auxetic foam sensors (AFS) created through conformably coating a thin conductive nanomaterial-sensing layer on a porous substrate having a negative Poisson's ratio. In general, the auxetic foam sensors possess multimodal sensing capability, such as large deformation sensing, small pressure sensing, shear/torsion sensing and vibration sensing and excellent robustness in humidity environment.

The present invention includes scalable and cost-effective auxetic foam sensors (AFS) created through conformably coating a thin conductive nanomaterial-sensing layer on a porous substrate having a negative Poisson's ratio. In general, the auxetic foam sensors possess multimodal sensing capability, such as large deformation sensing, small pressure sensing, shear/torsion sensing and vibration sensing and excellent robustness in humidity environment.

A device for determining an effective piezoelectric coefficient of a thin film of a material of a sample, includes a source of x-rays incident on the sample; a detector of x-rays diffracted by the sample; a device for positioning the x-ray source and the x-ray detector with respect to the sample; a voltage source making contact with the sample; a device for controlling the voltage source so as to apply an electric field to the sample during an electrical cycle, the electric field generating a strain of the sample and a stress on the sample; a device for measuring a diffraction peak of the x-rays as a function of the electric field applied to the sample during the electrical cycle; a processing device configured to determine the piezoelectric coefficient.

A device for determining an effective piezoelectric coefficient of a thin film of a material of a sample, includes a source of x-rays incident on the sample; a detector of x-rays diffracted by the sample; a device for positioning the x-ray source and the x-ray detector with respect to the sample; a voltage source making contact with the sample; a device for controlling the voltage source so as to apply an electric field to the sample during an electrical cycle, the electric field generating a strain of the sample and a stress on the sample; a device for measuring a diffraction peak of the x-rays as a function of the electric field applied to the sample during the electrical cycle; a processing device configured to determine the piezoelectric coefficient.

A method for detecting an open circuit state failure in a piezoelectric element connection includes exciting a piezoelectric element with an excitation signal and monitoring and evaluating an electrical output signal generated by the piezoelectric element in response to the excitation signal. The excitation signal is a pulse train. A frequency of the pulse train is chosen such that the piezoelectric element acts as a low pass filter.

A sense circuit for a piezoresistive sensor is provided that comprises: an energy storage circuit coupled to the piezoresistive sensor via a first node; a charge control circuit coupled to the first node and configured to charge the energy storage circuit to a predetermined potential; a discharge control circuit configured to allow the energy storage circuit to discharge through the piezoresistive sensor; and a readout circuit coupled to the first node and configured to output a sensed voltage based on a level of charges stored by the energy storage circuit.

Provided is a piezoelectric property measuring apparatus for a liquid or viscous material. The piezoelectric property measuring apparatus includes a fixing jig having an inner space and an opened space; an operating jig configured to close the opened region of the inner space; a first electrode and a second electrode; a driving module moving the operating jig according to a driving signal; a motion information measuring module measuring motion information of the operating jig; a charge amount measuring module measuring the charge amount through the first electrode and the second electrode; and a control module generating the driving signal for the driving module, supplying the driving signal to the driving module, receiving the motion information, receiving charge amount information of the closed space, and measuring a piezoelectric property of the sample by using the motion information and the charge amount information.

Provided is a piezoelectric property measuring apparatus for a liquid or viscous material. The piezoelectric property measuring apparatus includes a fixing jig having an inner space and an opened space; an operating jig configured to close the opened region of the inner space; a first electrode and a second electrode; a driving module moving the operating jig according to a driving signal; a motion information measuring module measuring motion information of the operating jig; a charge amount measuring module measuring the charge amount through the first electrode and the second electrode; and a control module generating the driving signal for the driving module, supplying the driving signal to the driving module, receiving the motion information, receiving charge amount information of the closed space, and measuring a piezoelectric property of the sample by using the motion information and the charge amount information.