A displacement sensor having a rectangular shaped elastic member. A piezoelectric element is attached to a first main face of the elastic member. The piezoelectric element has a rectangular-shaped piezoelectric sheet and electrodes on both main faces of the piezoelectric sheet. The piezoelectric sheet is made of poly-L-lactic acid and is at least uniaxially-stretched. The piezoelectric element is attached so that the uniaxial-stretching direction of the piezoelectric sheet is 45 relative to a long-side direction of the elastic member. When the elastic member is bent along the long-side direction, the piezoelectric sheet is stretched along the long-side direction, and the piezoelectric element generates voltage of predetermined level.

A batteryless rotary encoder is provided, which includes a rotation detecting section and a signal processing section. The rotation detecting section includes a rotational exciter magnet and a piezoelectric transducer. The piezoelectric transducer is constructed by laminating a magnetic material and a piezoelectric transduction sheet, and the magnetic material faces toward the rotational exciter magnet. When the rotational exciter magnet rotates, the rotational exciter magnet attracts or repels the magnet sheet or the magnetic metal sheet so that the piezoelectric transducer is pressed or stretched by the magnet sheet or the magnetic metal sheet to generate a first output signal. The signal processing section includes a counter and a rectifier. The counter receives the first output signal and calculates revolutions of the first output signal to indicate the number of rotations of the rotational exciter magnet. The rectifier receives the first output signal to power the counter.

A piezoelectric sensor assembly is for an electrical system. The electrical system includes a sensor attachment assembly and a number of electrical conductors. The sensor attachment assembly includes a sensor housing and a fastening member for fastening the sensor housing to a corresponding one of the electrical conductors. The piezoelectric sensor assembly includes a processor enclosed by the sensor housing, a piezoelectric sensor element, a wiring assembly electrically connecting the piezoelectric sensor element to the processor, an insulating member coupled to the piezoelectric sensor element and being structured to extend outwardly from the sensor housing to engage the corresponding one of the electrical conductors, and a mounting enclosure structured to mount the piezoelectric sensor element and the insulating member to the sensor housing.

A muscle activity observation apparatus that includes a sensor module and a detection module. The sensor module includes a piezoelectric sensor. Moreover, the piezoelectric sensor has an output that changes in accordance with a tremor of a tendon or a muscle, and an output that changes in accordance with contraction and relaxation of the tendon or the muscle. A detector of the detection module detects an activity state of the tendon or the muscle using a tremor signal and a contraction-relaxation signal output from the piezoelectric sensor.

A displacement sensor having a rectangular shaped elastic member. A piezoelectric element is attached to a first main face of the elastic member. The piezoelectric element has a rectangular-shaped piezoelectric sheet and electrodes on both main faces of the piezoelectric sheet. The piezoelectric sheet is made of poly-L-lactic acid and is at least uniaxially-stretched. The piezoelectric element is attached so that the uniaxial-stretching direction of the piezoelectric sheet is 45 relative to a long-side direction of the elastic member. When the elastic member is bent along the long-side direction, the piezoelectric sheet is stretched along the long-side direction, and the piezoelectric element generates voltage of predetermined level.

A displacement sensor having a rectangular shaped elastic member. A piezoelectric element is attached to a first main face of the elastic member. The piezoelectric element has a rectangular-shaped piezoelectric sheet and electrodes on both main faces of the piezoelectric sheet. The piezoelectric sheet is made of poly-L-lactic acid and is at least uniaxially-stretched. The piezoelectric element is attached so that the uniaxial-stretching direction of the piezoelectric sheet is 45 relative to a long-side direction of the elastic member. When the elastic member is bent along the long-side direction, the piezoelectric sheet is stretched along the long-side direction, and the piezoelectric element generates voltage of predetermined level.

A system for operating a physical measuring chain includes a plurality of physical measuring components at a measuring location. Each of the physical measuring components includes at least one physical sensor, at least one physical transmission means and at least one physical evaluation unit. An identification code is detected of each physical measuring component, and a data network transmits detected identification codes to a data processing unit located remote from the measuring location. The data processing unit includes at least one software and measuring component data. The software reads out measuring component data for transmitted identification codes and thereby generates a digital measuring chain including at least one digital sensor, at least one digital transmission means and at least one digital evaluation unit and the data network transmits the digital measuring chain to a computer unit at the measuring location.

A passive magneto-electric transducer includes a piezoelectric layer and magnetic structures attached thereto with high permeability material. Strain can be generated between the structures on the piezoelectric layer when subjected to an external magnetic field. The piezoelectric layer is configured to generate charges as a response to its mechanical strain from the forces of the magnetic structures. At least one pair of electrodes is positioned to collect charges of opposite sign, generated by the piezoelectric layer, so that a signal can be provided by the transducer without external electrical power sources.