A medical treatment system including a treatment chamber, a source of an aqueous mist containing a medication, a source of an oxygen-enriched gas, and a control system adapted to alternately surround a human body part with a mist containing a medication and the oxygen enriched gas, which can be used to treat various skin disorders including infected lesions, bacterial infections such as acne (i.e. Propionibacterium acnes), fungal infections such as Athlete's foot (i.e. fungal genus Trichophyton), conditions associated with hair loss including alopecia as well as ulcerations and frostbite resulting from poor circulation. A method of treating skin disorders is also disclosed, that includes providing a mist containing a medication and enriched oxygen gas to the site being treated as well as providing oxygen to the patient during treatment.

A closed loop catheter useable for heat exchange is manufactured by forming a plurality of generally transverse bore holes though a flexible, multilumen catheter body, lacing a tube trough the bore holes so that loops of the tube protrude from the catheter body, connecting one end of the tube to an inflow lumen of the catheter and connecting the other end of the tube to an outflow lumen of the catheter. A heated or cooled heat exchange medium may then be circulated through the tube while the catheter is inserted in the vasculature of a subject, thereby resulting in heat exchange between the subject's flowing blood and the heat exchange medium being circulated through the tube.

The invention includes novel devices and methods for inhibiting or preventing colonization of fluid flow networks by bacteria that have upstream surface motility. In certain aspects, the devices and methods of the invention prevent or minimize undesirable bacterial colonization of medical devices and/or treat or prevent bacterial infections.

Disclosed herein are methods for treating solid mass tumors with direct delivery of an anti-tumor immunotherapeutic agent to the tumor site. In one aspect, this invention encompasses methods of treating solid mass tumors by direct microinjection via a microcatheter of an anti-tumor immunotherapeutic agent into the microvasculature leading into tumor thereby providing high levels of contact with the tumor while minimizing the degree of systemic buildup of the immunotherapeutic agent.

A sheath introducer for a catheter includes a sheath having a lumen, a hub positioned on a proximal end of the sheath, and a housing positioned on the hub. The hub can include a splittable penetration member having a port in fluid communication with the sheath lumen. The housing can include a valve having a closed upper surface and a channel surrounding the splittable penetration member. Movement of the housing with respect to the hub can expose the port of the splittable penetration member for insertion of the catheter.

A catheter includes a catheter body having a proximal end, a beveled distal end, and a lumen therethrough. The beveled distal end defines an elliptical port for releasing contrast or other media through the lumen and from the elliptical port. The catheter may also be used delivering devices or for aspirating or extracting materials from the vasculature or other body lumens. A fixed guidewire extends distally from the distal end of the catheter body, typically from the distal-most edge of the elliptical port. The fixed wire is typically malleable so that it can be manually formed into a desired shape. The elliptical port may be flat or concave.

Systems and methods for longevity, anti-aging, fatigue management, obesity, weight loss, weight management, delivery of nutraceuticals, and treating hyperglycemia, Alzheimer's disease, sleep disorders, Parkinson's disease, Attention Deficit Disorder and nicotine addiction involve synchronizing and tailoring the administration of nutraceuticals, medications and other substances in accordance with the body's natural circadian rhythms, meal times and other factors. Improved control of blood glucose levels, extended alertness, and weight control, and counteracting of disease symptoms when they are at their worst are possible. An automated, pre-programmable transdermal administration system is used to provide pulsed doses of medications, pharmaceuticals, hormones, neuropeptides, anorexigens, pro-drugs, stimulants, nutraceuticals, phytochemicals, phytonutrients, enzymes, antioxidants, essential oils, fatty acids, minerals, vitamins, amino acids, coenzymes, or other physiological active ingredient or precursor. The system can utilize a pump, pressurized reservoir, a system for removing depleted carrier solution, or other modulated dispensing actuator, in conjunction with porous membranes or micro-fabricated structures.

An ultrasound catheter with a lumen for fluid delivery and fluid evacuation, and an ultrasound source is used for the treatment of intracerebral or intraventricular hemorrhages. After the catheter is inserted into a blood clot, a lytic drug can be delivered to the blood clot via the lumen while applying ultrasonic energy to the treatment site. As the blood clot is dissolved, the liquefied blood clot can be removed by evacuation through the lumen.

A medical device comprising a subcutaneous access port having an access port body and at least one needle having a removable needle tip and a needle shaft defining a needle lumen; the at least one needle housed within the access port body, the at least one needle extendable and retractable relative to the access port body; and a needle shift mechanism operable such that the at least one needle is extendable from and retractable into the access port body at a plurality of positions of the access port body.

The present disclosure is directed to a medical port drainage assembly that includes a port component and a replaceable catheter. The port component includes a tube having a proximal end, a distal end, and tube walls defining a catheter access lumen. A head component is located on a proximal end of the tube and an assembly retention element is located on a distal end of the tube. The head component is deployed outside the patient's body and defines an opening to the catheter access lumen. The assembly retention element is deployed within a lumen of the patient's body. The port component includes a valve assembly which may be a single valve (e.g., a duckbill valve) or a system of valves. The port component also includes a connector for coupling and decoupling the replaceable catheter to the port component.

Disclosed herein is a fluid infusion device of the type that delivers medication fluid to the body of a patient. The device includes or cooperates with a fluid reservoir, and the device has a sealing assembly to receive and form a fluid seal with the fluid reservoir. A retractable sealing element surrounding a hollow fluid delivery needle may be used to seal a port of the fluid reservoir. The port may include a pressure vent that is sealed by the retractable sealing element. In one variation, the reservoir includes a moving valve sleeve that holds a septum. The septum moves to allow the reservoir to vent, and to form a seal with the port when the needle pierces the septum. In another variation, the device includes a needleless sealing assembly. In yet other variations, the device uses a needled fluid reservoir.

A sensored electrical jumper comprises a conductor having a first end and a second end, the first end including a first connection interface and the second end including a second connection interface, a sensor section including at least one sensor disposed over the conductor between the first and second ends, the sensor section sensing at least one of current and voltage of the conductor, and a sensor output conduit extending from the sensor and oriented substantially perpendicular to the conductor axis to protect at least one sensor output wire from leakage current or other potential electrical damage.

A sensing apparatus for characterizing current flow through a conductor includes a plurality of magnetic sensors. In some embodiments, the sensors are grouped in pairs to achieve common mode rejection of signals generated in response to magnetic fields not resulting from current flow through the conductor. Sensors having different levels of sensitivity are used to collect information regarding the magnetic field generated by the current flowing through the conductor, where such information is processed in order to characterize the magnetic field. In some cases the sensors are included on or in flexible material that can be wrapped around the conductor.

A method of making a current sensor comprises providing a leadframe having a current conductor portion comprising two sections shaped such that a current to be measured flows in directions oriented obliquely or oppositely with respect to each other,deforming the leadframe to lower the current conductor portion,mounting an isolator on the current conductor portion,mounting a semiconductor chip having a thickness of at least 0.2 mm and comprising two magnetic field sensors composed of four Hall sensors and magnetic field concentrators on the isolator,connecting the semiconductor chip and sensor terminal leads by wire bonds,packaging the semiconductor chip and parts of the leadframe in a plastic housing, andcutting a frame of the leadframe from current terminal leads and the sensor terminal leads.

Precision AC and DC voltage, current, phase, power and energy measurements and calibrations with current ranges from 1 uA to 20 kA and voltage ranges from 1V to 1000 kV are now performed with accuracies of better than one part per million. Continued demand for improved accuracy has led the inventors to address remnant magetization within the current comparators that form the basis of the measuring process within many of the measurement instruments providing the precision AC and DC measurements and calibrations. Accordingly, the inventors present current comparator and measurement system architectures together with control protocols to provide for correction of this remnant magnetization.

A branch current monitor that includes reconfiguration.

Embodiments include apparatuses, systems, and methods including a switching converter having an output stage including a power switch or first switching device to convert an input switching signal to an output switching signal and a sensor stage including a second switching device and a third switching device. In embodiments, the sensor stage may be coupled to receive the output switching signal from the first switching device and to substantially replicate a condition of the first switching device to generate a continuous signal rather than a switched signal. In embodiments, the continuous signal may allow detection of a current level. In some embodiments, the current level may indicate an overcurrent event. A digital post-processing circuit may be coupled to the switching device to count a number of overcurrent events according to various embodiments. Other embodiments may also be described and claimed.

An electronic arrangement and method for providing a signal characterized by reduced phase noise having a signal source for providing a stimulus signal, a modulator coupled to the signal source for generating a modulated signal as function of the stimulus signal and a local oscillator signal, and a mixer combining the stimulus and modulated signals to generate a mixed signal that includes a component characterized by a mathematical difference of the stimulus signal and the modulated signal. The modulated signal is substantially identical to the stimulus signal and offset by a frequency of the local oscillator signal, so that the difference component of the mixed signal results in a local oscillator signal wherein the stimulus signal phase noise generated by the signal source has been mathematically cancelled.

A method for preparing an object to be tested, having a given relative permittivity, intended to be illuminated by an incident electromagnetic wave. The method includes: providing a part including a cavity for housing the object and at least one extension element made from a material having a relative permittivity that is preferably equal to that of the object, the extension element at least partially delimiting the cavity and extending to either side of the cavity in a passage direction of the cavity, over a length at least equal, on either side of the cavity, to one third of the length of the cavity in the passage direction, and placing the object in the cavity, such that the object is in contact with the extension element in the passage direction.

Methods and systems for monitoring an integrity of electrical connectivity between a repair patch and a parent structure include providing the repair patch with an embedded sensor configured to detect electrical conductivity. The repair patch includes a ply of conductive material that overlaps a portion of a conductive layer of the parent structure. A baseline set of sensor data is acquired from the sensor indicative of an electrical connectivity between the ply of conductive material of the repair patch and the conductive layer of the parent structure. One or more additional sets of data may be obtained from the sensor and compared to the baseline set of data to determine an integrity of the electrical connectivity between the ply of conductive material of the repair patch and the conductive layer of the parent structure.

Disclosed are a circuit fault detection system and method for a circuit fault detection. A circuit fault detection system includes: a detection circuit including a diode, a first resistor, and a second resistor, which are positioned between an applied voltage source and a top of a detection target circuit in series, and a third resistor and a fourth resistor, which are positioned between the detection target circuit and a ground in series, an input unit including a first input terminal configured to receive a voltage measured between the first resistor and the second resistor as an input, and a second input terminal configured to receive a voltage measured between the third resistor and the fourth resistor as an input, a controller configured to detect a failure in the detection target circuit and in an operation of the detection target circuit based on values of the voltages detected by the input unit; and a display unit configured to provide a warning to a user when the failure is detected.

A method of detecting an electric arc in an electrical system from a signal originating from at least one sensor detecting acoustic waves in the system, including: a) calculating by means of a processing device, over a sliding window of signal samples, at least one statistical parameter selected from the skewness and the kurtosis of the signal; b) detecting a possible occurrence of an event by taking into account said at least one statistical parameter; and c) performing a frequency analysis of the signal enabling to identify an electric arc when an event is detected at step b).

Systems and methods are disclosed for on-line monitoring of the condition of insulation in electrical devices employing a differential current sensor. In certain embodiments a monitor that can be fitted to existing electrical devices by attachment of the sensor to a pair of phase cables is provided. In other embodiments, an electrical device configured with an insulation monitor is provided.

A system can include at least one circuit breaker. The system can also include a prognostic and health monitoring (PHM) system. The PHM system can include at least one measuring device that measures at least one parameter associated with the at least one circuit breaker. The PHM system can also include a controller that receives measurements made by the at least one measuring device and analyzes the measurements to evaluate a performance of the at least one circuit breaker. The measurements can be made while the at least one circuit breaker is in service.

A sensor apparatus adjusts output timings of a detection signal and a sensing signal for sensing an abnormality in the detection signal. Provided is a magnetic sensor apparatus comprising a magnetic sensor element, an amplifying section that amplifies and outputs an output of the magnetic sensor element, a plurality of comparing sections that compare the output of the magnetic sensor element or an output of the amplifying section to a threshold value, and a plurality of delaying sections that each delay and output a comparison result output by a corresponding comparing section among the plurality of comparing sections. Also provided is a current sensor apparatus including a current path through which a current serving as a measurement target flows and a magnetic sensor apparatus that is arranged corresponding to the current path and detects a magnetic field generated according to the current serving as the measurement target.

A magnetic field sensing apparatus and detection method thereof are provided. The magnetic field sensing apparatus includes an anisotropic magneto-resistive (AMR) magnetic field detector, a reference magnetic field detector, and a controller. The AMR magnetic field detector generates a first output voltage according to a detected magnetic field. The reference magnetic field detector generates a second output voltage according to the detected magnetic field. The controller identifies whether an absolute value of a field density of the detected magnetic field is larger or smaller than a predetermined value or not, and selects the first output voltage or a saturation voltage to be a magnetic field detection result accordingly.

A method for determining a position of an RF coil in a magnetic resonance imaging (MRI) system is disclosed. As an example, a center of a field of view (FOV) to be scanned may be adjusted to a magnetic field center of an MRI system, and coordinate values in a coordinate system for shape-characteristic points of the FOV may be determined, where an origin of the coordinate system is located at the magnetic field center of the MRI system. A preset gradient magnetic field may be applied to the FOV, and coil units respectively covering the shape-characteristic points may be determined. An effective region may be obtained by connecting the determined coil units according to the shape of the FOV, and a coil unit located in the effective region may be determined as an effective coil unit for imaging the FOV by the MRI system.

According to one embodiment, magnetic resonance imaging apparatus includes a transmission coil, a plurality of reception channels, transmission/reception circuitry, and processing circuitry. The transmission coil transmits an RF wave to a subject. The reception channels receive MR signals generated from the subject. The transmission/reception circuitry controls the transmission coil to change the flip angle of a nucleus contained in the subject and excited by the transmitted RF wave. The processing circuitry determines whether the reception channels include an impaired channel, based on the comparison between the distributions of the signal values of the received MR signals with respect to the changing flip angles among the reception channels.

A system and method for magnetic resonance imaging is provided. The method includes dividing k-space into a plurality of regions along a dividing direction; scanning an object using a plurality of sampling sequences; acquiring a plurality of groups of data lines; filling the plurality of groups of data lines into the plurality of regions of the k-space; and reconstructing an image based on the filled k-space.

A universal, modular, temperature controlled MRI phantom for calibration and validation for anisotropic and isotropic imaging comprises an outer insulating shell configured to be received within an MRI chamber; an inner shell received within the outer insulating shell; a fluid conduits adjacent the inner shell for receiving temperature controlling fluid or gas cycling there-through; and a series of stacked layers of frames containing test points for the MRI phantom, each layer including at least one fiducial and including at least some anisotropic imaging test points in at least one frame and at least one isotropic imaging test point in at least one frame. The anisotropic imaging comprises hollow tubular textile fibers, wherein each hollow tubular fiber has an outer diameter of less than 50 microns and an inner diameter of less than 20 microns, wherein at least some hollow tubular fibers are filled with a fluid.

Acquiring seismic data using time-distributed sources and converting the acquired data into impulsive data using a multiple-frequency approach. The methods are performed in frequency-source location domain, frequency-wavenumber domain, or frequency-slowness domain. The methods are applicable to single source acquisition or simultaneous source acquisition.

A measurement while drilling (MWD) system for use in a drilling string, the MWD system comprises: a resistivity module that is configured to generate resistivity information about a resistivity of a formation that is drilled by the drilling string; a near bit sub that is configured to generate inclination information about an inclination of a drill bit of the drilling string; a MWD module; a first wireless communication module that is configured to wirelessly send the resistivity information from the resistivity module to the MWD module; a second wireless communication module that is configured to wirelessly send inclination information from the near bit sub module to the MWD module; and wherein the MWD module is configured to participate in a transmission of the inclination information and the resistivity information towards an upper surface of the formation.

The present disclosure provides a display panel, a method and a device for measuring screen flickering, and a display device. The display panel includes a substrate, data lines and gate lines arranged on the substrate and crossing each other, and subpixel units defined by the data lines and the gate lines. Each subpixel unit includes a TFT, a pixel electrode, a first common electrode and a second common electrode. The second common electrode is connected to an input end capable of providing an alternating voltage at a first frequency. An orthogonal projection of the second common electrode onto the substrate at least partially overlaps an orthogonal projection of the pixel electrode onto the substrate.

Disclosed is a piezoelectric material including stereocomplex crystals of poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA), wherein poly(D-lactic acid) and poly(L-lactic acid) are crystallized into a stereocomplex, thus exhibiting superior heat resistance and piezoelectric properties. This piezoelectric material, which is obtained using poly(lactic acid), can be produced at very low cost compared to when using PVDF, and is configured to include stereocomplex crystals of PDLA and PLLA and can thus manifest high thermal stability and piezoelectric properties, compared to when using conventional PLLA alone. Such a piezoelectric material can be efficiently utilized in a variety of fields in which low production cost, high processing temperature in the manufacturing process, or high-temperature stability of piezoelectric material products is required.

Methods and systems for frequency-dependent fluid attenuation measurement are provided. In certain embodiments, the methods comprise: generating one or more reference acoustic signals within a reference fluid; receiving one or more reference acoustic signal reflections; determining a frequency-dependent response function based, at least in part, on the one or more reference acoustic signal reflections; generating one or more sample acoustic signals within a sample fluid; receiving one or more sample acoustic signal reflections; and determining a frequency-dependent attenuation function of the sample fluid based, at least in part, on the one or more sample acoustic signal reflections and the frequency-dependent response function.

The present invention provides a cushion pad with improved durability without feeling of a foreign object. The present invention thus provides a system for detecting a deformation of a cushion pad, comprising; the cushion pad comprising a matrix layer, in which electroconductive or magnetic filler is dispersed, and a soft polyurethane foam including the matrix layer incorporated therein, anda detecting portion that detects an electric or magnetic change caused by a deformation of the cushion pad,wherein the matrix layer has a hardness lower than the soft polyurethane, and it production method.

A gyroscope includes a substrate, a first structure, a second structure and a third structure elastically coupled to the substrate and movable along a first axis. The first and second structure are arranged at opposite sides of the third structure with respect to the first axis A driving system is configured to oscillate the first and second structure along the first axis in phase with one another and in phase opposition with the third structure. The first, second and third structure are provided with respective sets of sensing electrodes, configured to be displaced along a second axis perpendicular to the first axis in response to rotations of the substrate about a third axis perpendicular to the first axis and to the second axis.

An ultrasonic measurement system and a measurement method thereof are disclosed. The system includes a subsystem summarization processing device, and at least two measurement subsystems mounted on different regions to be measured, each measurement subsystem includes a primary measurement sensor and a secondary measurement sensor, the primary measurement sensor includes a first housing, and a first transduction element, a measurement processing element and a signal control element mounted within the first housing respectively, the signal control element is coupled to the first transduction element and the measurement processing element respectively, the first transduction element is mounted on a bottom end surface of the first housing, the secondary measurement sensor includes a second housing and a second transduction element mounted on a bottom end surface of the second housing, the second transduction element is coupled to the signal control element, and the measurement processing element of each of the measurement subsystems is coupled to the subsystem summarization processing device respectively. The measurement accuracy can be improved by implementing the present invention.

A flow speed measurement method includes conducting a heat exchange at a prescribed part of a surface of a pipe, the flow speed measurement method further includes measuring a temperature distribution in a pipe-axis-direction on the surface of the pipe in a case that the heat exchange has been conducted at the prescribed part, and the flow speed measurement method further includes determining a flow speed of a thermal fluid flowing inside the pipe, based on the temperature distribution measured.

The invention provides a breather tube indicator device which includes a sealing body which is adapted to fit within a breather tube of a grouted rock support installation to allow passage of air past the body, without the body moving relatively to the tube, but to resist passage of an adhesive material thereby to cause movement of the body relatively to the tube to an indicating position.

In a method of operating a sensor assembly for a fluid tank of a motor vehicle, plural sensor elements of the sensor assembly are electrically connected to a sensor controller. The sensor controller determines measuring data from the sensor elements, and transmits the measuring data from at least some of the sensor elements separately and at least in part sequentially to a reprogrammable control unit.

Pre-loaded force sensitive input devices, force sensing resistors (FSR), are formed as a multiple membrane assembly that is capable of detecting low intensity pressure inputs and quantifying varying applications of pressure to the sensor surface. Pre-loading the force sensor elements results in controlled amount of force between the two substrates causing a constant state of pre-load and eliminating the low-end or minimal pressure signal noise associated with unloaded sensors. Pre-loading the force sensing resistor sensors also enables the sensor to detect removal of low intensity pressure input such as might occur during theft of light weight articles placed in contact with the pre-loaded force sensor. Using an FSR or FSR Matrix Array will enable any handling of protected retail packaging to be detected and identified. A library of “touches” can be established that will yield cutting, ripping, twisting, etc. making the detection of a theft in progress more accurate.

Provided is a torque sensor terminal block structure including an electric motor (1) which outputs driving force for driving a load (8), a strain body (3) interposed on a way of a power transmission system from the electric motor (1) to the load (8), a power detector (4) which outputs a detection signal according to a strain of the strain body (3) as a signal indicating a driving force transmitted from the electric motor (1) to the load (8), and a terminal block (6) which acquires the detection signal of the power detector (4) and transmits the output result to a signal processing circuit section. The terminal block (6) is set parallel to a magnetic flux output from the electric motor (1).

Provided is a torque sensor terminal block structure including an electric motor (1) which outputs driving force for driving a load (8), a strain body (3) interposed on a way of a power transmission system from the electric motor (1) to the load (8), a plurality of power detectors (4) which output a detection signal according to strain of the strain body (3) as a signal indicating the driving force, and a terminal block (6) which acquires the detection signal of the power detectors (4) and transmits the output result to a signal processing circuit section (10). The wirings to the signal processing circuit section (10) are twisted spirally as a single stranded wire, and an opening degree between single wirings when the stranded wire extending from the power detectors (4) to the terminal block (6) is unwound, is set to be same for each of the power detectors (4).

A sensor for detecting a pressure of a fluid medium is provided. The sensor includes a sensor element for detecting the pressure of the fluid medium, a supply duct for supplying the fluid medium to the sensor element and a control and/or evaluation circuit for processing signals of the sensor element. The control and/or evaluation circuit is situated on the sensor element.

A system comprising: a parent structure made of composite material and having a repair site; a repair patch made of composite material, the repair patch being bonded to the parent structure at the repair site; and a sensor embedded in the repair patch. The system may further comprise non-volatile memory and an interface unit embedded in the repair patch and electrically connected to the sensor. In one embodiment, the sensor is a loop-shaped sensor comprising an electrically conductive structure having an electrical conductivity that varies as a function of a pressure exerted on the repair patch. In another embodiment, the sensor comprises a sensor chip having nonvolatile memory. In a further embodiment, the sensor comprises an optical fiber that is sensitive to changes in pressure on or strain in the repair patch.

A detecting element unit of a physical quantity detection apparatus includes a detection part and a supporting part. The detection part has a base part, a movable part coupled to the base part via a joint part, and a vibrator provided over the base part and the movable part, and the supporting part includes a fixing portion to be fixed to a base for supporting the base part. A processing unit of the physical quantity detection apparatus extracts vibration response signals at a resonance frequency of the detecting element unit from output of the vibrator.

A sensor arrangement with a sensor element for measuring at least one physical and/or chemical fluid characteristic in a turbomachine is provided. The sensor element detects the at least one fluid characteristic inside a non-contact seal, in particular a labyrinth seal, between a rotor stage and a stator stage, wherein during operation the sensor element is in contact with the fluid flow along the flow path inside the labyrinth seal.

The invention relates to a drilling-resistance measuring device (10) and to a method for material testing in a humid environment or underwater. The drilling-resistance measuring device (10) comprises a housing (1), in which a drive and a drill chuck (3) coupled to the drive are arranged, in which drill chuck a drilling needle (4) is or can be releasably held, wherein the housing (1) has a drilling-needle outlet opening (5') enclosed by a drilling-needle outlet guide (5), through which drilling-needle outlet opening the drilling needle (4) extends out of the housing (1). The drilling-resistance measuring device (10) comprises at least one water-tight bellows (6), which is arranged in the interior of the housing (1) around the drilling needle (4) between the drill chuck (3) and the drilling-needle outlet guide (5), wherein moisture or water can enter the bellows (6) through the drilling-needle outlet opening (5').

A rheometer includes a drive shaft, a drag cup motor for rotating the drive shaft, a first measuring object supported by the drive shaft, a second measuring object, a linear position sensor, and processing and control electronics. The linear position sensor includes a target (e.g., an aluminum target) mounted to the drive shaft, and a pair of coils. The linear position sensor is configured to measure thermal expansion of the drive shaft based on a change in impedance of the coils resulting from a displacement of the target relative to the coils. The processing and control electronics are in communication with the coils and are configured to adjust a position of one of the measuring objects relative to the other based on a change in impedance of the coils resulting from a displacement of the target relative to the coils, thereby to maintain a substantially constant measurement gap therebetween.