Abstract: The present invention includes an apparatus that holds the probes to a solid support throughout the passages of the functionalization process, thus avoiding user-dependent breakage or damage of the fragile AFM cantilevers. The apparatus allows the tips of the AFM probes to be placed face-down, which avoids the deposition of contaminants on their functional side. The device also allows functionalizing the tips with small liquid volumes and cleaning. The present invention includes a functionalization process preventing non-specific adsorption of molecules on the tip.

Abstract: A device for oscillation excitation of a leaf spring, which is fastened on one side in an atomic force microscope (AFM) and comprises semiconductor material, which has no piezoelectric properties, a free end to which a tip is attached, which is brought into contact with a sample surface to be examined. The present invention has the leaf spring connected at least sectionally to a metal layer to form a Schottky contact, and an electrical voltage or field source is provided, which generates an electrical AC voltage a vicinity or area of the Schottky contact.

Abstract: A scanning probe microscopy instrument includes a cantilevered tip that has a nanowire light emitting diode (LED).

Abstract: A device including a first part and a second part, one of which is a cantilever, the first and second parts being connected to each other and movable relative to each other. The device includes a magnetic element arranged on the first part and configured to provide a magnetic field. The device further includes a magnetization device arranged on the second part and configured to provide an actuation magnetic field which interacts with the magnetic field of the magnetic element, thereby causing or suppressing relative movement of the first and second parts. A scanning system including such a device is also described.

Abstract: A method for measuring surface profile of a sample, wherein jumping of a probe can be constrained without applying strong force to the sample, and an apparatus employing such a method. Control operation consists of detection of displacement in a probe in the vertical direction on the top surface of a sample being measured by means of a sensor, calculation of velocity and acceleration of the probe in accordance with detection of the displacement in the probe, detection of jumping of the probe through real-time monitoring of at least either velocity or acceleration of the probe, and a control of the current delivered to a stylus pressure generator for the probe. Such a control operation is performed in a small amount of time, and a stylus pressure applied to the probe is increased only while the probe is in the air, while the stylus pressure applied to the probe is returned to an original pressure before the probe touches the sample again.

Abstract: A method and apparatus for inspecting a surface of an object. Data from measuring the surface of the object is obtained to form surface data for the object. A range of frequencies for features on the object is selected based on a range of distances between adjacent peaks for the features. The features are formed by a tool moving along a number of paths. Desired surface data for the features is obtained from the surface data using the range of frequencies selected. A determination is made as to whether the desired surface data for the features meets a policy specifying a desired surface for the object. In response to an absence of a determination that the desired surface data for the features meets the policy, the object is reworked.

Abstract: A system for generating surface data defining a position and location of an object is described. The system includes a non-contact measuring device for measuring the location of one or more points on a surface of an object with respect to the measuring device, an optical imaging device for capturing image information, and a processor. The processor is programmed to use the captured image information to determine location and orientation data for both the measuring device and the optical imaging device with respect to a fixed point in space, receive location measurement data from the measuring device, and combine the location and orientation data with the location measurement data to generate surface data for the object.

Abstract: A digital system for controlling the quality factor in a resonant device. The resonant device can be a a device that includes a cantilever within its system, such as an atomic force microscope. The quality factor can be digitally controlled to avoid noise effect in the analog components. A direct digital synthesizer implemented in a way that provides access to the output of the phase accumulator. That output is a number which usually drives a lookup table to produce a cosine or sine output wave. The output wave is created, but the number is also adjusted to form a second number that drives a second lookup table to create an adjustment factor to adjust the output from the cosine table. The adjusted digital signal than drives a DA converter which produces an output drive for the cantilever.

Abstract: The present invention relates to a disk protrusion detection/flatness measurement circuit and a disk glide tester, in which protrusion detection and average value calculation can be performed without switching signal processing circuits of two systems, one for the protrusion detection of a disk and the other for the average value calculation with respect to a track or a sector of the disk. This also makes it possible to reduce the size of the measurement circuit. In the protrusion detection/flatness measurement circuit, a signal from a protrusion detection sensor is amplified and converted from an analog signal to a digital signal. The signal passes through a band-pass filter to obtain a digital signal with a predetermined bandwidth. Then, peak detection and average value calculation processes are applied in parallel to the obtained digital signal. Thus, pass/fail decision of the disk can be made based on the detected peak and average values.

Abstract: An actuatable capacitive transducer including a transducer body, a first capacitor including a displaceable electrode and electrically configured as an electrostatic actuator, and a second capacitor including a displaceable electrode and electrically configured as a capacitive displacement sensor, wherein the second capacitor comprises a multi-plate capacitor. The actuatable capacitive transducer further includes a coupling shaft configured to mechanically couple the displaceable electrode of the first capacitor to the displaceable electrode of the second capacitor to form a displaceable electrode unit which is displaceable relative to the transducer body, and an electrically-conductive indenter mechanically coupled to the coupling shaft so as to be displaceable in unison with the displaceable electrode unit.

Abstract: Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation).

Abstract: An apparatus and technique for extracting information carried in higher eigenmodes or harmonics of an oscillating cantilever or other oscillating sensors in atomic force microscopy and related MEMs work is described.

Abstract: A sensor for registering a measurement variable of a medium, comprising a sensing body with a section of surface area, which is exposed to the medium to register the measurement variable, whereby a condition of the section of surface area affects the provided value of the measured measurement variable, whereby the section of surface area comprises a coating that comprises nanoparticles. The coating, which comprises the nanoparticles, comprises at least one nano polymer.

Abstract: Optical radiation sources functioning on different optical bands radiate on different optical bands and focus optical radiation on a region in a web surface as pulses in such a manner that illumination areas of the pulses overlap on the plane of the web. At most one optical radiation band is focused on the web from the direction of the normal. The spatial intensity distribution of at least one optical band differs from the uniform distribution and the intensity distributions of at least two different optical bands differ from one another in a predetermined manner. A camera forms still images of the web surface region on each optical radiation band. An image-processing unit determines the surface topography of the web on the basis of the images. In addition, a controller may control the paper manufacturing process on the basis of the determined surface topography.

Abstract: A system and method for analyzing a sample is described. The system may include, for example, a light source and a scanning probe microscope probe. The light source may generate a coherent laser beam that is modulated by a waveform of a lower frequency. The modulated laser beam is absorbed by the sample causing thermally induced expansion and resulting in an excitation of acoustic waves. The probe is locally deployed near the sample and detects, in real time, perturbations in the excited acoustic waves to detect surface and buried structures of the sample.

Abstract: Interatomic forces are measured with subatomic lateral resolution by in situ calibrated non-contact and passively thermal drift compensated atomic force microscopy in aqueous or generally liquidous environment; interatomic forces acting between distinct electronic orbitals of front-most tip atom and opposing sample atom can be quantitatively measured with subatomic lateral resolution. Calibration standard is a CaCO3-crystal, which undergoes a well defined pressure induced phase transition from the calcite to the aragonite crystal lattice structure providing an accurate independent force anchor point for the AFM's force versus distance curve. Furthermore, an independent actual tip-sample-distance d calibration is obtained by directly observing oscillatory (steric) solvation forces originating simply from packing effects of the liquid particles at very small tip-sample separations d.

Abstract: A scanning probe microscope includes a plate moveable in an x-axis direction, a y-axis direction, and a z-axis direction, and a probe tip coupled to the plate. A plurality of actuators cooperate to move the probe tip with three degrees of freedom of movement.

Abstract: An AFM based technique has been demonstrated for performing highly localized IR spectroscopy on a sample surface. Significant issues as to size, cost of implementation, and repeatability/robustness of results exist in commercializing the technique. The invention addresses many of these issues thereby producing a version of the analytical technique that can be made generally available to the scientific community.

Abstract: A cylinder sleeve surface measurement assembly for measuring a surface roughness of a cylinder sleeve, especially a cylinder sleeve formed in an engine block. The assembly includes a fixture that holds a surface profiling device. The surface profiling device is provided with a stylus that perpendicularly projects from a measuring arm, and the fixture holds the surface profiling device such that the stylus remains in perpendicular contact with the surface of the cylinder sleeve. To ensure perpendicular contact, the fixture is provided with an arcuate surface that defines an arc matching that of a portion of the cylinder sleeve. Accordingly, the arcuate surface allows the measuring arm to remain parallel to a surface of the cylinder sleeve, thereby ensuring that the stylus remains perpendicular thereto.

Abstract: An AFM based technique has been demonstrated for performing highly localized IR spectroscopy on a sample surface. Significant issues as to size, cost of implementation, and repeatability/robustness of results exist in commercializing the technique. The invention addresses many of these issues thereby producing a version of the analytical technique that can be made generally available to the scientific community.

Abstract: The present invention is directed to scanning probes in which a cantilever contacts a stylus via an integrated stylus base pad, and methods for fabricating such probes. The probe offer many advantages over other types of scanning probes with respect to eliminating the need for a soft, reflective coating in some applications and providing for the simple fabrication of sharp stylus tips, flexibility with respect to functionalizing the tip, and minimal thermal drift due to reduced bimorph effect. The advantage of these features facilitates the acquisition of high resolution images of samples in general, and particularly in liquids.

Abstract: A metrology probe capable of measurements of a broad range of physical properties of individual samples of nano- or sub-nanometer dimensions is provided. The probe comprises a probe body, a substrate connected to the probe body, and a tip proximate the substrate. The probe further comprises a coarse piezoelectric actuator having an electrical input. The coarse piezo is configured to cause the tip and/or the substrate to move relative to each other when a first electrical signal is provided to the electrical input. The probe further comprises a low-pass filter in electrical communication with the electrical input of the coarse piezo. The probe further comprises a fine piezoelectric actuator having an electrical input configured to cause the tip and/or the substrate to move relative to each other when a second electrical signal is provided to the electrical input.

Abstract: A sensor for scanning a surface with an oscillating cantilever (12), made from piezoelectric material that is suitable for a transverse oscillation of the free end of a beam, holding an electrically conductive probe tip (14) on the free end of the beam in transverse direction, a first deflection electrode (26A, 26B) and an inversely phased second electrode (28A, 28B, 28C) being provided to collect charges that are separated within the space of the deflection electrodes (34, 36). The cantilever (12) is provided with at least one electrode (30) in addition to the deflection electrodes (26A, 26B, 28A, 28B, 28C) that provides electrical contact to the tip (14), the at least one additional electrode being located in a region on the deflecting beam where the surface charge density due to the strain caused by beam deflection (34, 36) is smaller than in the region where the deflection electrodes are located.

Abstract: Described herein are devices and methods for sensing pulsed forces. Some of the described devices and methods are also useful for measuring infrared absorbances and compiling spectral and chemical maps of surfaces. Also described are microcantilever having reduced harmonic frequencies when operating in contact mode. Some of the described microcantilevers comprise an internal resonator configured to vibrate substantially independent of friction between the microcantilever tip and a surface when the microcantilever operates in contact mode. A number of the described devices and methods are useful for monitoring pulsed forces with enhanced sensitivity.

Abstract: An atomic force microscope (AFM) apparatus for determining a topography of a sample surface is disclosed. The AFM apparatus comprises: a controller having a controller frequency response and being configured to provide a controller output signal. The controller comprises an integrator that provides an integrator output signal, and a filter block. The AFM apparatus also comprises a physical system having a physical system response and being configured to receive the controller output signal and to provide a probe height in response to the controller output signal. The physical system comprises an actuator configured to maintain a deflection of a probe tip relative to the sample surface. The deflection being is indicated by a deflection signal, and the filter block of the controller provides an inverse of the physical system response, such that the probe height is substantially equal to the integrator output signal.

Abstract: The invention is a novel method and apparatus for optimal placement of actuators responsible for shaping of elastically deformable structures into desired target shapes using sparse number of actuators such that the discrepancy between deformed surfaces and target shapes is minimized. The invention utilizes a computational algorithm for optimal placement of actuators using particle swarm optimization, a biologically inspired evolutionary optimization paradigm that searches for the minima (or maxima) of objective functions with possibly large number of parameters.

Abstract: A surface texture measuring device includes a rotation driving device configured to rotate a measured substance, a roughness detector including a stylus provided displaceably at a tip of a detector main body and at least one skid provided at the tip of the detector main body and in the proximity of the stylus and outputting displacement of the stylus based on the skid as an electric signal, and a detector driving device configured to drive a detector holder. The detector holder includes a guide member driven by the detector driving device, a slide member configured to hold the roughness detector and provided slidably in a displacement direction of the stylus to the guide member, and an urging member configured to urge the slide member so that the skid always comes in contact with the measurement face of the measured substance.

Abstract: A device (60) and method for measuring the roughness of a playing surface are described. The device includes a carriage (12) which can travel over the playing surface, a rotatable member (80) which can roll over the playing surface, a restraint (84) which constrains the rotatable member (80) to travel with the carriage (12) and a transducer (70) coupled to the rotatable member (80) and which can generate a signal representative of the height and/or lateral translation of the rotatable member.

Abstract: A method of forming a microchannel as well as a thin film structure including same is made by forming a first thin film on a side of a substrate, forming a fugitive second thin film on the first thin film such that the second thin film defines a precursor of the elongated microchannel and a plurality of extensions connected to and extending transversely relative to the precursor along a length thereof A third thin film is formed on the first thin film and the fugitive second thin film such that the second thin film resides between the first thin film and the third thin film. A respective access site is formed in a region of the third thin film residing on a respective extension and penetrating to the fugitive second thin film. The fugitive second thin film forming the precursor is selectively removed from between the first thin film and the third thin film using an etching medium introduced through the access sites, thereby forming the microchannel between the first thin film and the third thin film.

Abstract: To date, the probes of scanning near-field optical microscopes were aimed at creating electromagnetic field characteristics that are maximally localized near a nano-sized point (miniature apertures and tips, fluorescent nano-particles and molecules, dielectric and metal corners). Alternatively, the probe field, which is distributed within a larger area, can ensure the super-resolution as well. For this purpose, the field spectrum should be enriched with high spatial frequencies corresponding to small sample dimensions. As examples of such near-field probes, we propose and theoretically study the models of optical fibers with end-faces containing sharp linear edges and randomly distributed nanoparticles. These probes are more robust than the conventional probes and their fabrication is not concerned with nanoscale precision. The probes enable waveguiding of light to and from the sample with marginal losses distributing and utilizing the incident light more completely.

Abstract: A surface texture measuring device includes a threshold value storage module configured to store a threshold input through an operation key, a stylus move distance detector configured to detect a move distance in the trace direction of the stylus, a cumulative move distance storage module configured to cumulatively store the move distance of the stylus detected by the stylus move distance detector; and. a notification module (controller) configured to make a comparison between the threshold value stored in the threshold value storage module and the cumulative move distance stored in the cumulative move distance storage module and notifying a user of replacement of the stylus when the cumulative move distance has exceeded the threshold value.

Abstract: A substrate mimicking intercellular lipids in stratum corneum consisting of a substrate and a lipid membrane formed on the substrate, wherein the lipid membrane is formed from ceramide, palmitic acid and cholesterol, and the ceramide, palmitic acid and cholesterol are present at a mass ratio of 20-70%:10-600:20-40% (ceramide:palmitic acid:cholesterol).

Abstract: A surface measurement method includes inspecting a plurality of samples of a first irregular workpiece surface in two dimensions, determining, based on the inspections of the samples, a total number of surface peaks on each of the plurality of samples, and deriving a control limit from a statistical variation of the total number of surface peaks on each of the samples. The control limit specifies an out-of-tolerance condition for the total number of surface peaks on a second irregular workpiece surface. The method further includes inspecting a portion of the second irregular workpiece surface in two dimensions, determining, based on the inspection of the portion of the second irregular workpiece surface, a total number of surface peaks on the portion, and comparing the total number of surface peaks on the portion to the control limit to determine whether the second irregular workpiece surface is in the out-of-tolerance condition.

Abstract: In the case of measuring a pattern having a steep side wall, a probe adheres to the side wall by the van der Waals forces acting between the probe and the side wall when approaching the pattern side wall, and an error occurs in a measured profile of the side wall portion. When a pattern having a groove width almost equal to a probe diameter is measured, the probe adheres to both side walls, the probe cannot reach the groove bottom, and the groove depth cannot be measured. When the probe adheres to a pattern side wall in measurements of a microscopic high-aspect ratio pattern using an elongated probe, the probe is caused to reach the side wall bottom by detecting the adhesion of the probe to the pattern side wall, and temporarily increasing a contact force between the probe and the sample. Also, by obtaining the data of the amount of torsion of a cantilever with the shape data of the pattern, a profile error of the side wall portion by the adhesion is corrected by the obtained data of the amount of torsion.

Abstract: The scanning probe microscope has a primary control loop (7, 11, 12) for keeping the phase and/or amplitude of deflection at constant values as well as a secondary control loop (9) that e.g. keeps the frequency of the cantilever oscillation constant by applying a suitable DC voltage to the probe while, at the same time, a conservative AC excitation is applied thereto. By actively controlling the frequency with the first control loop (7, 11, 12) and subsequently controlling the DC voltage in order to keep the frequency constant, a fast system is created that allows to determine the contact potential difference or a related property of the sample (3) quickly.

Abstract: A method, and corresponding apparatus, of imaging sub-surface features at a plurality of locations on a sample includes coupling an ultrasonic wave into a sample at a first lateral position. The method then measures the amplitude and phase of ultrasonic energy near the sample with a tip of an atomic force microscope. Next, the method couples an ultrasonic wave into a sample at a second lateral position and the measuring step is repeated for the second lateral position. Overall, the present system and methods achieve high resolution sub-surface mapping of a wide range of samples, including silicon wafers. It is notable that when imaging wafers, backside contamination is minimized.

Abstract: The invention is directed to a probe for scanning probe microscopy. The probe 20 comprises a tunnel-current conducting part 30 and a tunnel-current insulating part 40. The said parts are configured such that the insulating part determines a minimal distance between the conducting part 30 and the sample surface. The invention may further concern a scanning probe microscope having such a probe, and a corresponding scanning probe microscopy method. Since the distance to the sample surface 100 is actually determined by the insulating part 40, controlling the vertical position of the probe 20 relative to the sample surface is easily and rapidly achieved. The configuration of the parts allows for a fast scan of the sample surface, whereby high-speed imaging can be achieved. Further, embodiments allow for topographical variations to be accurately captured through tunneling effect.

Abstract: Determining a repairing form of a defect at or close to an edge of a substrate. The defect may be scanned with a scanning probe microscope to determine a three-dimensional contour of the defect. The defect may be scanned with a scanning particle microscope to determine the shape of the at least one edge of the substrate. The repairing form of the defect may be determined from a combination of the three-dimensional contour and the shape of the at least one edge.

Abstract: Methods and systems for, in one embodiment, accelerating a stage through a clearance height in a first direction and decelerating the stage in the first direction while accelerating in a second direction are shown. The stage is moved in a third direction and a determination is made whether the stage movement in the second direction is below a threshold value before continuing to move the stage further in the third direction. The first direction is perpendicular to the second direction and is parallel and opposite to the third direction.

Abstract: Transferable probe tips including a metallic probe, a delamination layer covering a portion of the metallic probe, and a bonding alloy, wherein the bonding alloy contacts the metallic probe at a portion of the probe that is not covered by the delamination layer are provided herein. Also, techniques for creating a transferable probe tip are provided, including etching a handler substrate to form one or more via arrays, depositing a delamination layer in each via array, depositing one or more metals in each via array to form a probe tip structure, and depositing a bonding alloy on a portion of the probe tip structure that is not covered by the delamination layer. Additionally, techniques for transferring transferable probe tips are provided, including removing a handler substrate from a probe tip structure, and transferring the probe tip structure via flip-chip joining the probe tip structure to a target probe head substrate.

Abstract: Provided is a method for manufacturing a semiconductor device. The method, in one embodiment, includes calibrating an inspection tool configured to obtain a measurement of a semiconductor feature, including: 1) providing a test structure comprising a substrate having a trench therein, and a post feature located over the substrate adjacent the trench. The post feature, in this embodiment, includes a second layer positioned over a first layer, wherein the first layer has a notch or bulge in a sidewall thereof; 2) finding a location of the notch or bulge relative to a different known point of the test structure using a probe of the inspection tool; and 3) calculating a dimension of the probe using the relative locations of the notch or bulge and the different known point.

Abstract: A glide head with a slider body that has a leading edge, a trailing edge and an air bearing surface is disclosed. The glide head also has an array of thermal proximity sensing elements connected in a bridge circuit that are adjacent both the trailing edge and the air bearing surface, a heating element mounted to the glide body for elevating the temperature of the thermal proximity sensing elements in relation to the temperature of an inspected surface, and a controller coupled to the array of thermal proximity sensing elements. The controller receives signals from the thermal proximity sensing elements, and determines the existence of a surface variation in the inspected surface based upon differences in the signals received from the thermal proximity sensing elements.

Abstract: A localized nanostructure growth apparatus that has a partitioned chamber is provided, where a first partition includes a scanning probe microscope (SPM) and a second partition includes an atomic layer deposition (ALD) chamber, where the first partition is hermetically isolated from the second partition, and at least one SPM probe tip of the SPM is disposed proximal to a sample in the ALD chamber. According to the invention, the hermetic isolation between the chambers prevents precursor vapor from damaging critical microscope components and ensuring that contaminants in the ALD chamber can be minimized.

Abstract: An atomic force microscopy (AFM) method includes a scanning probe that scans a surface of a structure to produce a first structure image. The structure is then rotated by 90° with respect to the scanning probe. The scanning probe scans the surface of the structure again to produce a second structure image. The first and second structure images are combined to produce best fit image of the surface area of the structure. The same method is used to produce the best fit image of a flat standard. The best fit image of the flat standard is subtracted from the best fit image of the structure to obtain a true topographical image in which Z direction run out error is substantially reduced or eliminated.

Abstract: A cylindrical internal surface processing apparatus has an internal diameter measuring device and a controller. The internal diameter measuring device measures an internal diameter of an internal cylindrical bore formed in a base member to obtain a measurement result of the internal diameter of the internal cylindrical bore. The controller includes a surface roughening control section and a quality determining section. The surface roughening control section controls operation of a surface roughening equipment to form a rough surface section and an internal diameter measuring surface section on the internal cylindrical bore. The internal diameter measuring surface section is smoother than the rough surface section.

Abstract: A method for measuring variations of the surface of an object using acoustic energy in the audio range is provided. Imaging fine surface roughness on the order of few microns is achievable by using a vibroacoustography technique. This technique provides a method for imaging surface roughness on the basis of an ultrasound radiation force that stimulates acoustic emissions at an ultrasound standing wave field. The present invention may be employed as a tool for the nondestructive inspection and imaging of the surface variations of an object.

Abstract: Proposed is a procedure for carrying out a scanning probe microscopic or atomic force spectroscopic measurement within predetermined parameters, which said procedure encompasses the following steps: a determination of a value variance of at least one of the parameters, and control of an adjustment member in relation to said variance, so that the variance is at least partially compensated for.

Abstract: A method for making a specimen assembly for atom probe analysis in an energetic-beam instrument includes milling a post near a region of interest in a sample in the energetic-beam instrument, so that the post has a free end. The probe tip of a nano-manipulator probe shaft is attached to the free end of the post and the post is cut free from the sample to form a rough specimen, so that the region of interest in the rough specimen is exposed at approximately the location where the post is cut from the sample. A specimen assembly form is provided having an open area inside its perimeter. The probe shaft bearing the specimen is joined to the specimen assembly form, so that the region of interest in the rough specimen is located in the open area. Thereafter, the probe shaft can be cut off outside the perimeter of the specimen assembly form, and the specimen conveniently held and sharpened for atom probe analysis. Specimen assembly forms made by the method are also disclosed.

Abstract: A microscope, in particular a scanning probe microscope, comprising a programmable logic device.

Abstract: A surface texture measuring apparatus includes a stylus displacement detector having a measurement arm which is able to swing, a pair of styli provided at a tip of the measurement arm, and a detection unit configured to detect swing amounts of the measurement arm, a stage configured to mount the subject of measurement thereon, and a relative movement mechanism configured to cause a relative movement between the detector and the stage. The apparatus includes a posture switching mechanism configured to switch a posture of the measurement arm between a posture in which the measurement arm is urged in one swing direction and a posture in which the measurement arm is urged in the other swing direction, and a speed control mechanism configured to control a switching speed of posture switching of the measurement arm to a preset speed when the posture of the measurement arm is switched by the posture switching mechanism.