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The detailed design of a mechanically detected nuclear magnetic resonance probe using the SPAM (Springiness Preservation by Aligning Magnetization) geometry, operating at 4 K, in vacuum, and a several-Tesla magnetic field is described. The probe head is vibration-isolated well enough from the environment by a three-spring suspension system that the cantilever achieves thermal equilibrium with the environment without the aid of eddy current damping. The probe uses an ultra-soft Si cantilever with a Ni sphere attached to its tip, and magnetic resonance is registered as a change in the resonant frequency of the driven cantilever. The RF system uses frequency sweeps for adiabatic rapid passage using a 500 μm diameter RF coil wound around a sapphire rod. The RF coil and optical fiber of the interferometer used to sense the cantilever's position are both located with respect to the cantilever using a Garbini micropositioner, and the sample stage is mounted on an Attocube nanopositioner.

Parametric coupling has been demonstrated between mechanical vibration modes in a magnet-tipped microcantilever. An external magnetic field, coupled to the magnetic tip, pumps the effective spring constant at a frequency which is either the sum or the difference of the mode resonance frequencies. The presence of the pump field can be detected by driving one mode and observing the parametrically pumped excitation of the other mode, even though the pump frequency is off-resonance with respect to both mechanical modes. In a room temperature experimental realization, the magnetic flux coupling the pump field to the tip was approximately one flux quantum and the dominant noise source was the thermal vibration of the cantilever. Parametric mode coupling is a useful new design option in magnetic resonance force microscopy, whereby modulation is advantageously performed off-resonance to avoid parasitic excitations caused by stray couplings. Parametric coupling also provides a low-noise technique for amplifying mechanical oscillations. The reported experiment completes the set of all possible force microscope interaction Hamiltonians up to third order in time-dependent fields.

In magnetic resonance force microscopy (MRFM) experiments, magnetic forces couple to the motion of microscale cantilever beams. Extension of MRFM to the detection of single electrons will require both unprecedented force sensitivity and motional stability of the cantilever. We describe the principles and performance of optimal cantilever motion control. The method accounts for inherent noise processes and practical application of control forces. We show that active feedback control improves cantilever motional stability, enabling instrument designs of much higher sensitivity and faster imaging than passive designs. Experimental results of implemented cantilever control systems are presented in Part II.

We describe the implementation of optimal controllers for damping the motion of cantilevers used in magnetic resonance force microscopy. We demonstrate that optimal control is achievable and that torsional magnetic coupling provides an effective actuation method. Cantilever Brownian vibrational amplitude was reduced from 2 to 0.16 A and resonant quality was reduced from 2000 to 5. Applied control fields were sufficiently small that they would not affect magnetic resonance phenomena.

This article presents a new modulation technique for noise reduction in magnetic resonance force microscopy. Applied fields are modulated at frequencies that are not rational fractions of the cantilever resonant frequency, thus avoiding overtones that contribute to the noise level. An on‐resonance signal is obtained because the nonlinear sample magnetization acts as a frequency mixer of the two modulation frequencies, producing a net force modulation at the cantilever resonant frequency. These techniques are experimentally demonstrated using electron spin resonance in a

Recent initial experiments in magnetic resonance force microscopy (MRFM) have detected the magnetic force exerted by electrons and nuclei in microscopic samples. The experiments generate a force signal by modulating the sample magnetization with standard magnetic resonance techniques. Sample sizes of a few nanograms generate readily detected force signals of order ${10}^{\ensuremath{-}14}$ to ${10}^{\ensuremath{-}16}$ Newtons. This article describes the present status of MRFM technology, with particular attention to the feasibility of detecting single-electron magnetic moments, and the possible applications of MRFM in biological imaging.

This article describes systems in which the precession of a single particle spin is magnetically coupled to the excitation of an oscillator. The behavior of such systems resembles that of a ‘‘folded’’ Stern–Gerlach experiment, in which the linear spatial trajectory of the original Stern–Gerlach experiment is folded into the cyclic trajectory of an oscillator. Both quantum and semiclassical solutions to the equations of motion are derived. The results encompass any kind of oscillator which couples to a magnetic field. Examples include mechanical cantilevers with a magnetic source affixed to them, as well as inductor‐capacitor resonant circuits. One potential application of oscillator‐coupled magnetic resonance is the imaging of biological molecules. Some design issues relevant to molecular imaging are discussed.

The use of fringe-field capacitive sensing for surface profile measurement during the turning process is described. Measurements of the local surface height are inferred from variations in a fringe electric field induced between the sensing element and the workpiece. The surface profile is determined from high-speed scanning of the sensing element across the surface. The technique is particularly well-suited to the relatively harsh environment of in-process measurement. We have implemented a system in which profile measurements are made continuously, in real-time, and immediately adjacent to the cutting tool. The results of tests conducted to determine the accuracy and sensitivity of this capacitive profilometer are presented. In-process measurements of surfaces generated by turning with roughness in the range of 0.3 to 4.0 μm were made. Comparisons with static profile measurements made using standard stylus instrumentation are presented, and show quantitative agreement.

Machining of graphite/epoxy composite material is investigated by turning (cutoff) tests using different grades of polycrystalline diamond (PCD) inserts. The wear behavior of the PCD cutting edge is characterized by small cracks, rounded edges, and flank wear. The flank wear growth rate was found to depend on the microstructure of the tool and machining time. The coarser the PCD grade was, the better the wear resistance. The machined surface characteristics were evaluated by analyzing the surface roughness data and by scanning electron microscopy inspection of machined surface textures. Surface quality was found to get better with the cutting time.

This paper presents a theoretical analysis of the equilibrium mechanics of bending and twisting fiber geometries in ligaments and tendons. The theory predicts that the bending of loaded fibers is necessarily accompanied by large transverse pressures and pressure gradients. The predicted pressures are especially large at the bone tunnel entries of ligament grafts, where they can equal or exceed the applied tensile loads. Experimental measurements of internal pressures confirm these predictions.

We describe a fiber-optic interferometer that employs wavelength changes to achieve maximum sensitivity. Wavelength changes are induced by adjusting the operating temperature of the laser, eliminating the need for an actuator to vary the spacing between the sensing fiber and the object to be monitored. The instrument and techniques described are suitable for cryogenic, high vacuum applications such as magnetic resonance force microscopy, where space is limited and micromanipulation can be challenging. The noise floor of 1.6×10−3 nm/Hz is adequate for monitoring subangstrom displacement of force microscope cantilevers.

We proposed to complete three tasks in this project. These tasks were MRFM imaging with nanometer-scale resolution end-to-end performance analysis of quantum spin imaging and a reference design for a year-20O6 quantum microscope. At the time of this report, nanometer-scale MRFM imaging has been achieved at 8Onm resolution. A performance analysis was completed, and published as an invited paper in the Proceedings of the IEEE on the Classical and Quantum Theory of Thermal Magnetic Noise. With recent work in spin simulation exactly matching recent experiments performed at IBM, this technical report represents the deliverable of a complete Reference Design and Performance Analysis (RDPA) as originally proposed.

Bearings commonly are modeled as a linear viscous element. This behavior is easily confirmed with a simple, inexpensive experiment using only a wristwatch and a bicycle equipped with a speedometer. With the bicycle inverted so that its rear wheel is free to spin, this experiment involves observing and recording the variation of the angular velocity of the rear wheel as it decelerates from some initial speed. This experiment is a group activity, requiring teamwork to record the data by hand. From the data recorded and an estimate of the moment of inertia of the wheel, students determine the time constant of the system, the degree to which first-order response is exhibited by the system, and the equivalent damping coefficient for the bearings that support the rear wheel. Because of the familiarity of the components of the system being examined, the simplicity of the experiment, the teamwork required in the experiment, and the high degree of agreement between the analytical predictions and the experimental results, this experiment is an excellent experiment in system dynamics.Copyright © 2003 by ASME

As part of the Manufacturing Engineering Educational Partnership (MEEP) design and manufacturing courses have been restructured into a sequence leading to a Program in Products Realization (PPR) in our undergraduate engineering curriculum. The purpose is to provide a broad based, interdisciplinary program for undergraduate students interested in the design and manufacturing of industrial products. Although each school has taken a slightly different approach to the implementation, the students at the three schools experience design and manufacturing activities each semester (or quarter) in residence. The program bridges the gap between engineering science and practice, and allows students to work in teams on real industrial problems. The implementation of the program has required restructuring of existing courses, the addition of new resources, and the creation of Learning Factories at each of the institutions. The Learning Factories provide modern facilities for design, manufacturing, fabrication, and testing of products. In addition, the program has attracted the support of over 100 industrial sponsors, who have helped promote hands-on experience and provided projects and class room support. This paper describes the new program at each of the institutions, the resources required, and operational experiences to date. This project was supported by the ARPA Technology Reinvestment Program and the National Science Foundation.

We report theory and observations of paramagnetic resonance in a measured field gradient of 44,000 T per meter by the technique of magnetic resonance force microscopy (MRFM). Resonance was induced in a dilute solid solution of diphenylpicrylhydrazyl in polystyrene at 77 and 10 K by an amplitude-modulated microwave field. This modulated the force between resonant sample spins and a micrometer-scale SmCo magnetic tip on a force microscope cantilever. The force signals were typically of order 10 fN, and were detected above a thermal noise floor of 80 aN per root hertz at 10 K, equivalent to a magnetic moment noise of 200 μ B per root hertz of bandwidth. Resonance saturation was readily observed. Starting with the Bloch equations, we derived simple analytic expressions for the predicted cantilever signal amplitudes and T 1 -dependent phase lags, valid at low microwave power levels. For power levels below saturation, the data were in good agreement with the Bloch equation predictions, while above saturation the measured force increased more slowly with power than predicted. Several ESR mechanisms which might lead to non-Bloch dynamics in the MRFM environment are reviewed. Spin-relaxation mechanisms are also reviewed. A detailed description of the experimental apparatus is offered.

Capstone design courses in engineering, which provide students the opportunity to tackle open-ended, real-world projects, are generally held in high regard as learning experiences. A relatively new and increasingly important component of engineering is the area of mechatronics. In this paper, we review the goals of capstone design courses and examine how well suited mechatronics projects are for use as projects in capstone design courses. Our experiences in using mechatronics projects in the senior-level capstone design course in the Department of Mechanical Engineering at the University of Washington are presented. From these experiences, we demonstrate that mechatronics projects are particulary well suited for use in capstone design.

Mechatronics is the synergistic combination of mechanical, electrical, and computer technologies in the design of complex products and processes. Recent rapid growth of mechatronics as an area of engineering has given rise to a significant demand for mechatronics engineers. At the university level, engineering programs have emerged that help meet this need by producing engineering graduates who are capable, well-rounded mechatronics designers. One such program is the multi-course guided curriculum in mechatronics that is available to students in their senior year in the Mechanical Engineering Department at the University of Washington. Described in this paper are that mechatronics program as a whole, the curriculum into which it fits, the individual constituent courses, and our observations after offering this program for two years.

Recently the first experiments in magnetic resonance force microscopy (MRFM) have been conducted. In these experiments a force microscope cantilever is used to detect the magnetic force exerted by electrons and nuclei in a sample. The magnetization of the sample is modulated at the resonant frequency of the cantilever, using standard magnetic resonance techniques. The resulting excitation of the cantilever is detected optically. This article reviews the present status of MRFM technology, emphasizing the physical principles involved and the opportunities for further research and development. Particular emphasis is placed on single spin detection by MRFM and potential applications in biomolecular imaging.

This report describes a cantilever controller for magnetic resonance force microscopy (MRFM) based on a field programmable gate array (FPGA), along with the hardware and software used to integrate the controller into an experiment. The controller is assembled from a low-cost commercially available software defined radio (SDR) device and libraries of open-source software. The controller includes a digital filter comprising two cascaded second-order sections ("biquads"), which together can implement transfer functions for optimal cantilever controllers. An appendix in this report shows how to calculate filter coefficients for an optimal controller from measured cantilever characteristics. The controller also includes an input multiplexer and adder used in calibration protocols. Filter coefficients and multiplexer settings can be set and adjusted by control software while an experiment is running. The input is sampled at 64 MHz; the sampling frequency in the filters can be divided down under software control to achieve a good match with filter characterisics. Data reported here were sampled at 500 kHz, chosen for acoustic cantilevers with resonant frequencies near 8 kHz. Inputs are digitized with 12 bits resolution, outputs with 14 bits. The experiment software is organized as a client and server to make it easy to adapt the controller to different experiments. The server encapusulates the details of controller hardware organization, connection technology, filter architecture, and number representation. The same server could be used in any experiment, while a different client encodes the particulars of each experiment., submitted to Review of Scientific Instruments

Magnetic resonance force microscopy (MRFM) and other emerging scanning probe microscopies entail the detection of attonewton-scale forces. Requisite force sensitivities are achieved through the use of soft force microscope cantilevers as high resonant-Q micromechanical oscillators. In practice, the dynamics of these oscillators are greatly improved by the application of force feedback control computed in real time by a digital signal processor (DSP). Improvements include increased sensitive bandwidth, reduced oscillator ring up/down time, and reduced cantilever thermal vibration amplitude. However, when the cantilever tip and the sample are in close proximity, electrostatic and Casimir tip-sample force gradients can significantly alter the cantilever resonance frequency, foiling fixed-gain narrow-band control schemes. We report an improved, adaptive control algorithm that uses a Hilbert transform technique to continuously measure the vibration frequency of the thermally-excited cantilever and seamlessly a...

Inertial sliders are often used to produce coarse relative positioning for scanning probe microscopes. This article describes the design, dynamic analysis, and control of a compact four-segment piezoceramic tube scanner employing an inertial slider. Velocity feedback control, implemented using two-segment piezoelectric sensing, was used to suppress undesired vibrations in the tube, and to improve scanner step uniformity. The control analysis was based on an empirical open-loop identification of the as-built tube behavior, which was also measured using the two-segment sensing technique. A reset integrator friction simulation predicted the overall system performance, and showed good agreement with experimental results.

Inertial reaction devices (also referred to as impact drive, or slip-stick devices) enable nano/micro resolution positioning over macroscopic ranges. Such positioning devices are characterized by the displacement of a mass by utilizing stick-slip phenomena between the mass and the device’s actuators. The displacement of the actuator (i.e., the driving wave form) is chosen such that the mass sticks to the actuator and is displaced with the actuator during the first tracking phase, and the mass slips with respect to the actuator during the second retrace phase during which the actuator’s position is reset. However, as the driving wave form’s frequency is increased to operate an inertial-reaction device at high speed, induced mechanical vibrations prevent accurate actuator positioning and thereby, limit the maximum achievable operating speed. In this article, the actuator dynamics is modeled and iteratively inverted to find the input that compensates for the induced mechanical vibrations. This inversion-base...

The term "robot" refers to a precision mechanical device that is accurately controlled by a computer using intelligent software. The term "robotic assistance" refers to the use of such a device to aid a surgeon in the optimal conduct of a procedure, particularly one requiring specified geometrical relationships. The authors have been exploring the application of robotic assistance in situations in which accuracy and precision are required in orthopaedic surgery. The initial application concerned the planning, positioning, and orientation cuts and holes of the bone required for the femoral component of a total knee arthroplasty. A three-dimensional digitizing template allowed the surgeon to specify the desired position and orientation of the component's articular surfaces in relation to the distal femur. The robotic system used this spatial relationship, along with its knowledge of the geometry of the component selected by the surgeon, to plan the precise location of the required bone cuts and holes. Finally, the robotic assistant sequentially positioned saw and drill guides with respect to the distal femur so that the surgeon made these cuts and holes in the locations necessary for optimal component fit, position, and orientation. The robotic assistant functioned easily in the operating room environment; increased the accuracy; and decreased the time, equipment, and personnel required for the conduct of the geometrical part of this surgical procedure.

A rugged, compact sensor for in-process measurement of surface finish profiles is proposed. The concept is based on the detection of variations in the fringe electric field generated between the surface and a perpendicular, ceramic-encased electrode. An analysis of both static and spatial dynamic characteristics of this “capacitive profilometer” is presented. For some surfaces, the device acts as a low-pass spatial filter, attenuating the higher spatial frequencies. A method of dynamic compensation, based on Fourier transform techniques, is developed. Experimental results demonstrate the validity of the analysis and dynamic compensation. Direct comparisons of surface profiles measured with the capacitive and standard stylus-type are presented and show good agreement.

The on-line hole inspection system consists of a circular rod made of ceramic material, containing four small capacitive sensors at its circumference. When inserted into the hole, the capacitance of each sensor element varies as a function of its distance from the hole wall. Each capacitor is connected to an electronic oscillator/demodulator unit whose output signal is sampled by a microcomputer. In its present version, the hole probe is designed to measure the geometry of holes up to 50 mm long, making measurements every 100 um. The accuracy of the hole diameter measurement is better than 10 um as long as the distance from the probe tip to the hole wall is below 0.5 mm. Because the capacitive probe tips are completely encapsulated by hard ceramic material, the sensor is rugged and suitable for operation in a production environment.

This article presents an investigation of potential ligament attachment sites for surgical reconstruction of the anterior and posterior cruciate ligaments as well as for the lateral extraarticular iliotibial band tenodesis. Our methodology was based on quantitative measurements of knee anatomy and motion in fresh cadavers, not on biomechanical modeling. Using computer search techniques, we located all the ligament insertion sites that were nearly isometric for motion of the intact knee.

The pulsed ultrasonic Doppler velocimeter has been used extensively in transcutaneous measurement of the velocity of blood in the human body. It would be useful to evaluate turbulent flow with this device in both medical and non-medical applications. However, the complex behaviour and limitations of the pulsed Doppler velocimeter when applied to random flow have not yet been fully investigated.In this study a three-dimensional stochastic model of the pulsed ultrasonic Doppler velocimeter for the case of a highly focused and damped transducer and isotropic turbulence is presented. The analysis predicts the correlation and spectral functions of the Doppler signal and the detected velocity signal. The analysis addresses specifically the considerations and limitations of measuring turbulent intensities and one-dimensional velocity spectra.Results show that the turbulent intensity can be deduced from the broadening of the spectrum of the Doppler signal and a mathematical description of the effective sample-volume directivity.In the measurement of one-dimensional velocity spectra at least two major complicacations are identified and quantified. First, the presence of a time-varying, broad-band random process (the Doppler ambiguity process) obscures the spectrum of the random velocity. This phenomenon is similar to that occurring in laser anemometry, but the ratio of the level of the ambiguity spectrum to the largest detected velocity spectral component can be typically two to three orders of magnitude greater for ultrasonic technique owing to the much greater wavelength.Secondly, the spatial averaging of the velocity field in the sample volume causes attenuation in the measured velocity spectrum. For the ultrasonic velocimeter, this effect is very significant.The influence of the Doppler ambiguity process can be reduced by the use of two sample volumes on the same acoustic beam. The signals from the two sample volumes are cross-correlated, removing the Doppler ambiguity process, while retaining the random velocity. The effects of this technique on the detected velocity spectrum are quantified explicitly in the analysis for the case of a three-dimensional Gaussianshaped sample-volume directivity.

An extensive experimental programme in both laminar and turbulent flow was undertaken to examine the validity of all of the major implications of the model of the pulsed ultrasonic Doppler velocimeter for turbulent flow developed in part 1 of this investigation. The turbulence measurements were made in fully developed flow at the centre of a 6·28 cm diameter pipe. The Reynolds number of the flow ranged from 6000 to 40000. The carrier frequency of the ultrasonic velocimeter was 4·7 MHz.Measurements of the turbulence intensity and of the one-dimensional velocity spectra made with the ultrasonic velocimeter are compared with the analysis and with the actual quantities as measured by a hot-film anemometer. The experimental results are in agreement with theoretical predictions.Measurements of one-dimensional turbulence spectra with reduced ambiguity spectra made by the two sample volume methods described in part 1 are presented. The results verify the analysis and indicate that an improvement in the useful dynamic range of the velocity power spectrum of nearly three orders of magnitude can realistically be achieved.