Abstract: A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

Abstract: The device is a miniature, self-contained solid state orientation sensor. The unit utilizes three magnetometers and three accelerometers to calculate pitch, roll, and yaw (compass heading) angles relative to the earth's magnetic and gravitational fields. The three orientation angles are output in digital RS232 or optional multi-drop RS485. The device can also be programmed to provide raw accelerometer and magnetometer data in true physical units. The device is capable of measuring angles from 0 to 360 degrees on the yaw axis, 0 to 360 degrees on the pitch axis, and −70 to +70 degrees on the roll axis. The yaw output is compensated for errors due to pitch and roll using embedded algorithms. Applications include fast solid state compassing, robotics, virtual reality, down-hole well drilling, and body position tracking for biomedical and multimedia applications.

Abstract: A sensing device includes an RFID chip and a differential variable reluctance transducer (DVRT) sensor that can be read remotely with electromagnetic power provided to the device from a remote reader. The ac signal provided to the device by inductance is used for powering the RFID chip and exciting the sensor. Data read from the sensor can also be transmitted back to the reader using the power provided by the reader. The sensor circuit uses a lower amount of current than the RFID chip, so it does not contribute appreciably to device power requirements.

Abstract: The device is a miniature, self-contained solid state orientation sensor. The unit utilizes three magnetometers and three accelerometers to calculate pitch, roll, and yaw (compass heading) angles relative to the earth's magnetic and gravitational fields. The three orientation angles are output in digital RS232 or optional multi-drop RS485. The device can also be programmed to provide raw accelerometer and magnetometer data in true physical units. The device is capable of measuring angles from 0 to 360 degrees on the yaw axis, 0 to 360 degrees on the pitch axis, and −70 to +70 degrees on the roll axis. The yaw output is compensated for errors due to pitch and roll using embedded algorithms. Applications include fast solid state compassing, robotics, virtual reality, down-hole well drilling, and body position tracking for biomedical and multimedia applications.

Abstract: The novel peak strain detection linear displacement sensor system for smart structures is designed to provide monitoring of the strain in structures and reporting their strain histories. The system comprises the use of micro miniature, high resolution, passive peak strain detector. A displacement sensor, such as a differential variable reluctance transducer, is used and the sliding core of the unit is constrained so that it shows the maximum movement in one direction. Once positioned and attached, mechanical movement of the core will always occur in response to structural deformation. The system comprises attachment devices and a body clamp and core extender and compressor, a housing, a spring loaded collar, a sensor core and a measuring unit.

Abstract: A micro-electromechanical system (MEMS) is described for economical sensing of angular accelerations, especially for use in biomechanical applications. The device design is inspired by that of the semi-circular canals of the inner ear, utilizing a fluid filled channel and differential pressure transducer. Using modem fabrication techniques, very sensitive angular acceleration instruments may be realized. By combining these fast response sensors with other sensors, such as DC response linear accelerometers, allows broader frequencies of human motion to be monitored.

Abstract: A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

Abstract: A sensing device is attached to a living subject that includes a first sensors for distinguishing lying, sitting, and standing positions. In another embodiment, sensor data is stored in a storage device as a function of time. Multiple points or multiple intervals of the time dependent data are used to direct a feedback mechanism to provide information or instruction in response to the time dependent output indicating too little activity, too much time with a joint not being moved beyond a specified range of motion, too many motions beyond a specified range of motion, or repetitive activity that can cause repetitive stress injury.

Abstract: The novel sensor assembly is comprised of a threaded housing with pressure relief tracks through the threads that terminate at a hole through the housing and a displacement sensor. In the preferred embodiment, we have included an integral connector, a super-elastic core carrier and a Differential Variable Reluctance Transducer. Other sensor types could be used to construct a pressure equalized displacement sensor as described herein, these may include: capacitive, resistive, Hall effect, eddy current, and differential variable transformer.

Abstract: A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

Abstract: Improved coils and clamps for variable reluctance sensors are disclosed. A method of fabricating a discrete coil involves providing a conductor wound in a coil on a tube. The coil has a coil outer surface that has insulation. A window is opened in the insulation on the coil outer surface to expose conductor of the coil for a contact. A movable core is provided within the tube for adjusting inductance of the coil. In one embodiment, the coil and tube are diced into small coils after the windows for each coil are opened. Another aspect the invention is a clamp comprising an elastic material, a shape memory alloy, and an apparatus for activating the shape memory alloy. The clamp holds the moveable core in its peak position. When the alloy is activated it changes shape and provides a force on the elastic material to change clamping state for resetting the transducer. The coils and clamps can be used for a variety of purposes in addition to the variable reluctance sensors.

Abstract: An apparatus consistent with the present invention comprises a sensor for receiving a signal representing eye tremor and a processor for monitoring eye tremor while receiving the signal. A method consistent with the present invention includes receiving a signal representing eye tremor, comparing the received signal representing eye tremor to at least one reference value, and classifying a patient's brain stem function using the comparison of the received signal representing eye tremor to at least one reference value.

Abstract: A data collection apparatus includes a sensing unit for attaching to a structure or live subject for sensing a parameter of the structure or live subject. The sensing unit includes a sensor, a data storage device, and a transmitting device. The data storage device is for storing data from the sensor. The apparatus also includes a control unit that is separable from the sensing unit. The control unit includes a data receiving device and a second data storage device different from said first storage device. The data receiving device is to receive data transmitted from the data sensing unit. The second data storage device is for storing the data received from the sensing unit. The apparatus also includes a triggering device for modifying the storing of data being stored to the first data storage device or for initiating transmission of data from the sensing unit to the control unit. The triggering device is controlled by a real time change in information about the structure or live subject.

Abstract: The novel peak strain detection linear displacement sensor system for smart structures is designed to provide monitoring of the strain in structures and reporting their strain histories. The system comprises the use of micro miniature, high resolution, passive peak strain detector. A displacement sensor, such as a differential variable reluctance transducer, is used and the sliding core of the unit is constrained so that it shows the maximum movement in one direction. Once positioned and attached, mechanical movement of the core will always occur in response to structural deformation. The system comprises attachment devices and a body clamp and core extender and compressor, a housing, a spring loaded collar, a sensor core and a measuring unit.

Abstract: A sensing device includes a Wheatstone bridge and a source of a stimulation configured to apply the stimulation across two electrodes of the Wheatstone bridge. The device also includes a timing sensitive circuit configured to detect timing of a signal appearing across one of the other electrodes of the bridge as a result of the stimulation being applied. The timing provides a way to read the sensor. The device can be powered remotely and data so read can be transmitted using the remote power. The timing sensitive circuit includes a comparator. The comparator provides a high logic signal for a time related to the reactance of one leg of the Wheatstone bridge, and that provides a reading of a differential sensor having elements in each leg of the bridge.

Abstract: The novel temperature gradient compensation circuit is designed to overcome temperature gradient problems in inductive or capacitive circuits, such as, differential variable reluctance transducers. The system comprises, in one embodiment, the use of an inductive or alternating current bridge which sends its output to a low pass filter in order to remove the alternating current component of the bridge output. The output of the low pass filter is fed into an instrumentation amplifier whose gain can be adjusted. The output of this instrumentation amplifier is a signal that is proportional to the temperature gradient experienced by the alternating current bridge. The output of the alternating current bridge is also fed to a high pass filter and then sent to a demodulator and amplifier. By subtracting the direct current output from the alternating current output, the effects of temperature do not have an effect upon the result.

Abstract: The novel inclined plate 360 degree absolute angle sensor is designed to measure the absolute angle created by a base and a rotating surface. The assembly contains a metal inclined plate positioned above four coils so that coils one and two are at the minimum and maximum distance from the plate respectively, while at the same time, coils three and four are equidistant from the inclined plate. Rotation of the plate around a centerline, changes the distance that all four coils with respect to the inclined plate which, in turn, creates a change of the inductance of the coils. This change in inductance may be measured with alternating current bridge technologies in order to provide a measure of absolute angular position of a rotating surface with respect to the base.

Abstract: The novel differential variable reluctance transducer assembly is comprised of an ultra miniaturized device encased in stainless steel. The assembly contains a free sliding, magnetically permeable core and two coils surrounding the core. A split ring mounting adapter system allows for a variable gauge length and interchangeable mounting pins. A highly flexible core carrier tube and support wire allows for significant bending without failure, does not interfere with the coils detection of the core, and protects the core from corrosion. A sleeve strain relief sheath has been incorporated with the sensor to avoid excessive strain to lead wires during and after installation. The position of the core is detected by measuring the coils' differential reluctance and transmitted by means of wires or telemetry to measuring equipment.

Abstract: The novel differential variable reluctance transducer and telemetry system is comprised of a ultra miniaturized device encased in stainless steel. The system contains a free sliding, magnetically permeable, stainless core and two coils surrounding the core. The position of the core is detected by measuring the coils' differential reluctance. The coils resonate at a frequency which depends on the position of the core and the difference in resonant frequency is used to modulate a high frequency carrier. This radio frequency signal is transmitted for remote reception by an FM receiver, amplified and put through a phase-locked-loop circuit into a microprocessor for counting and displaying.

Abstract: This apparatus is adapted for replaceable implantation in soft body tissues for the measurement of the mechanical behavior of the soft tissues of the body. The apparatus consists of a thin walled tube containing a longitudinal slot down one side with at least one piezo-resistive strain gauge element bonded to its inner or outer walls. Tension in tissue fiber bundles results in a squeezing pressure against the sides of the tube, which produces a change in the shape of the tube and thus a change in the resistance of the strain gauge element. This resistance change is then measured and displayed. A method of inserting and removing the apparatus is also described, as are several techniques for calibration.