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Point-of-care (PoC) applications require small, fast, and low power sensors with high reliability. Despite showing promising performances, nanomechanical sensors have not yet demonstrated the excellent reproducibility of measurements necessary to be incorporated-in such systems. Coffee-ring effect usually occurs during the deposition of the functionalization layer and produces an inhomogeneous and poorly repeatable profile on the sensor surface. In this study, we investigated how cantilever-based sensors and the previously developed membrane-type surface stress sensor (MSS) are affected by an inhomogeneous functionalization. We functionalized 8 piezoresistive cantilevers and 16 MSS with a dextran solution that formed an inhomogeneous layer due to the coffee ring effect. During expositions to humidity pulses, MSS was five times more reproducible (standard deviations between 5% and 6%) compared to the cantilever-based sensors (standard deviations between 25% and 28%). In fact, the cantilever-based sensors were as reproducible as their functionalization layer while the reproducibility of MSS was only limited by the tolerances of their fabrication. This sensor-to-sensor reproducibility, combined with a high sensitivity, makes the MSS a promising bio/chemical sensor platform for reliable and label-free detection of substances to be integrated into PoC systems. (C) 2015 Elsevier B.V. All rights reserved.

A new and versatile fabrication process of insulated gold tip probes for atomic force microscopy (AFM) is presented by Wu et al. (In-plane fabricated insulated gold-tip probe for electrochemical and molecular experiments, in: 2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE, 2013, pp. 492-495). The novelty of the process lies in the fact that the length and the thickness of the cantilever are defined by photolithography and Si etching from the wafer top surface. Width of the cantilever is defined by the device layer of a silicon-on-insulator (SOI) wafer. The tip is fabricated in the wafer top plane. E-beam lithography was employed outlining the gold nanowire tip. The chip body is formed with the handling layer of the SOI by deep reactive ion etching in later steps. In a practical operation, the probe chip is rotated by 90 degree. The tip radius of curvature is approximately 20 nm. The high-quality insulation on the probe was demonstrated by performing electrodeposition of gold on the tip-end. The spring constant of the cantilever was obtained by measuring resonance frequency of the cantilever. With this in-plane fabrication process, probes with different spring constants ranging from 0.05 N/m to 13.67 N/m were fabricated on the same wafer. (C) 2013 Elsevier B.V. All rights reserved.

With their capability for real-time and label-free detection of targets ranging from gases to biological molecules, nanomechanical sensors are expected to contribute to various fields, such as medicine, security, and environmental science. For practical applications, one of the major issues of nanomechanical sensors is the difficulty of coating receptor layers on their surfaces to which target molecules adsorb or react. To have measurable deflection, a single-side coating is commonly applied to cantilever-type geometry, and it requires specific methods or protocols, such as inkjet spotting or gold-thiol chemistry. If we can apply a double-side coating to nanomechanical sensors, it allows almost any kind of coating technique including dip coating methods, making nanomechanical sensors more useful with better user experiences. Here we address the feasibility of the double-side coating on nanomechanical sensors demonstrated by a membrane-type surface stress sensor (MSS) and verify its working principle by both finite element analysis (FEA) and experiments. In addition, simple hand-operated dip coating is demonstrated as a proof of concept, achieving practical receptor layers without any complex instrumentation. Because the double-side coating is compatible with batch protocols such as dip coating, double-side-coated MSS represents a new paradigm of one-chip-one-channel (channels on a chip are all coated with the same receptor layers) shifting from the conventional one-chip-multiple-channel (channels on a chip are coated with different receptor layers) paradigm.

Measuring the mechanical properties of molecule junctions and, in parallel, recording their electric response provides further insight for molecular electronics. On the other hand, the Conductive Probe (CP-AFM) experiments with electrochemically controlled molecular switches are still challenging topics due to technical difficulties with the insulation of the cantilever. In this work, we developed a gold-coated insulated conductive AFM probe to connect molecules and to measure their properties, which include both the mechanical force and the charge transport between the tip and a conducting substrate.

For many diseases, where a particular organ is affected, chemical by-products can be found in the patient’s exhaled breath. Breath analysis is often done using gas chromatography and mass spectrometry, but interpretation of results is difficult and time-consuming. We performed characterization of patients’ exhaled breath samples by an electronic nose technique based on an array of nanomechanical membrane sensors. Each membrane is coated with a different thin polymer layer. By pumping the exhaled breath into a measurement chamber, volatile organic compounds present in patients’ breath diffuse into the polymer layers and deform the membranes by changes in surface stress. The bending of the membranes is measured piezoresistively and the signals are converted into voltages. The sensor deflection pattern allows one to characterize the condition of the patient. In a clinical pilot study, we investigated breath samples from head and neck cancer patients and healthy control persons. Evaluation using principal component analysis (PCA) allowed a clear distinction between the two groups. As head and neck cancer can be completely removed by surgery, the breath of cured patients was investigated after surgery again and the results were similar to those of the healthy control group, indicating that surgery was successful.

We report on harsh-environment-compatible Pt-TSVs forming ohmic contacts with a highly doped bulk silicon. They were developed as a part of a Single Wall Carbone NanoTube (SWCNT) resonator device with 3D-packaging. The fundamental properties of the TSVs, experimentally obtained with bulk Si instead of the real working device, are presented. Our concept for the device fabrication is “via first”, followed by the nanodevice fabrication. As such, first ohmic contacts on silicon has been studied to be compatible with several harsh post-processing steps, including high temperature treatments—up to 850°C in air—and concentrated HF-based release steps. Then TSVs withstanding the aforesaid conditions have been developed. These interconnects are also of interest for MEMS devices operating at high temperature.

In this paper, we report on the integration technique and fabrication of a scanning probe interrogating the location of charges and their tracks inside quantum devices. Our unique approach is to pattern the charged sensor into a high topography micromechanical structure. A single-electron transistor (SET) is directly integrated onto the microfabricated cantilever that extends out from the body of a scanning force microscope (SFM) probe of standard dimensions. In a novel tactic and by reversing their traditional roles, a tuning fork (TF) completes the probe to provide the self-actuating and self-sensing qualities necessary for an oscillatory force sensor. We show sharp edges on the Coulomb diamonds, indication that the SET fabrication step yields devices of high quality. We demonstrate topographical scans with this probe. All stages of the fabrication process are executed on batches of probes which is an essential step away from the time-consuming and individual preparation of other implementations. It opens the door to a more reproducible and large volume production.

In this study, we introduce five unique scanning vibes developed in our laboratory for different fields of application These probes are the results of excellent collaborations with many external partners Each probe possesses many advanced features that one can hardly obtain with plane probes for conventional optical deflection system The applications of these probes are very versatile. from atomic force microscope for the exploration of Mars to In vivo measurements of human knee cartilage (C) 2010 Institute of Electrical Engineers of Japan Published by John Wiley & Sons. Inc

We recently introduced a new self-actuating and self-sensing atomic force microscope (AFM) probe based on a quartz tuning fork and a micro-fabricated cantilever. This system has two degrees of freedom, associated with its two components. We developed a model for describing how the sample-tip interaction is transduced to the tuning fork. It is based on two coupled spring-mass systems. In a first step, the coupling between the tuning fork and the cantilever was investigated to reveal the influential factors. The analysis of these factors enabled us to deduce their effect on the whole system and to optimize the sensitivity of this novel probe. The theoretical analysis was compared with experimental results and it was found that the model appropriately describes the probe in a qualitative manner while further refinement will be needed for achieving a correct quantitative description.

A micro pump was integrated into a scanning force microscope probe for circulating liquid through its hollow cantilever and tip. The interior cross section of the cantilever was 2.25 mu m x 3.75 mu m. All fluidic parts were made of SiO2, while the tip apex was made of Si3N4. The key fabrication techniques were silicon wafer bonding and wet-oxidation. The pumping mechanism was relying on the enhanced evaporation at an enlarged water/air interface at the exit of the microchannel. Capillary forces continuously wetted this interfacial area, thus drawing the liquid through the system. At room temperature, a pump rate of 11 pl s(-1) was experimentally evaluated. The observed temperature dependence of the pump rate could be qualitatively understood by a plain model calculation. (C) 2007 Elsevier B.V. All rights reserved.

A concept of an array actuator that is used to control the tip-sample separation of cantilevers in a two-dimensional (2D) probe array scanning system is proposed in this article. The feasibility of the concept is demonstrated with a 10 × 10 array actuator with 500 μm xy-pitches. The array actuator is made by slicing a bulk piezoceramic block. The obtained maximum actuation of a single probe was 2.19 μmp_p at ±168 Vp_p. A major issue for the actuator was the insufficient strength of the frame of the probe array chip. The demonstrated array actuator is highly compatible with previously developed parallel readout modules that use either a parallel optical beam or integrated piezoresistive deflection sensing. A large-scale 2D probe array is our ultimate target. © 2007 The Japan Society of Applied Physics.

The development of new tools and instruments for biomedical applications based on nano- (NEMS) or microelectromechanical systems technology (MEMS) are bridging the gap between the macro- and the nano-world. The well mastered microtechnique allows controlling many parameters of these instruments, which is essential for conducting reproducible and repeatable experiments in the life sciences. Examples are multifunctional scanning probe sensors for cell biology, an arthroscopic scanning force microscope for minimally invasive medical interventions and a nanopore sensor for single molecule experiments in biochemistry. This paper reviews some of the activities conducted in a fruitful interdisciplinary collaboration between physicists, engineers, biologists and physicians. © 2007 Elsevier B.V. All rights reserved.

Osteoarthritis is a painful and disabling progressive joint disease, characterized by degradation of articular cartilage. In order to study this disease at early stages, we have miniaturized and integrated a complete scanning force microscope into a standard arthroscopic device fitting through a standard orthopedic canula. This instrument will allow orthopedic surgeons to measure the mechanical properties of articular cartilage at the nanometer and micrometer scale in-vivo during a standard arthroscopy. An orthopedic surgeon assessed the handling of the instrument. First measurements of the elasticity-modulus of human cartilage were recorded in a cadaver knee non minimal invasive. Second, minimally invasive experiments were performed using arthroscopic instruments. Load-displacement curves were successfully recorded.

Piezoresistive scanning probe arrays have been developed in view of operation in liquid environments. When the cantilevers are immersed in electrically conductive solutions like for instance physiological buffers, the piezoresistive sensing elements as well as the metal connections have to be passivated. For that purpose, the sensors and the metal wiring were covered with different protective coatings. Long term stability of these passivation layers was demonstrated by imaging in a buffer solution for several hours. Moreover, in view of reducing the damping and thus decreasing the hydrodynamic resistance in liquids, special truss cantilevers have been developed. It was found that this special design conferred no improvement in terms of Q-factor and resonant frequency when operated in water. In order to explain the behaviour of these probes, a theoretical model was established. The model predicted that truss structures could theoretically improve the cantilever performances in liquid, but the probes would need to be operated at high frequency, above 10 MHz. © 2007 IOP Publishing Ltd.

We present a unique probe that is based on a quartz tuning fork and a microfabricated cantilever. The probe is self-actuating and self-sensing. The cantilever can be tailored to the needs of specific applications, in this case to feature an electrically connected tip, in order to apply a potential to it. We investigate the usability of our probe with a tip for local oxidation experiments. We performed cyclic voltammetry to determine the bias voltage beyond which local anodic oxidation can happen. Our goal is to use this probe in a future scanning probe microscopy (SPM) lithography apparatus.

This paper describes the characterization and application of electrically insulated conductive tips mounted on a cantilever for use in an atomic force microscope and operated in liquid. These multifunctional probes were microfabricated and designed for measurements on biological samples in buffer solution, but they can also be employed for electrochemical applications, in particular scanning electrochemical microscopy. The silicon nitride based cantilevers had a spring constant ≤0.1 N m-1 and a conductive tip, which was insulated except at the apex. The conductive core of the tip consisted of a metal, e.g. platinum silicide, and exhibited a typical radius of 15 nm. The mechanical and electrical characterization of the probe is presented and discussed. First measurements on the hexagonally packed intermediate layer of Deinococcus radiodurans demonstrated the possibility to adjust the image contrast by applying a voltage between a support and the conductive tip and to measure variations of less than 1 pA in faradaic current with a lateral resolution of 7.8 nm. © 2005 IOP Publishing Ltd.

A novel probe based on a commercial quartz tuning fork and a microfabricated cantilever is presented. The U-shaped cantilever with a monolithic tip is combined with the tuning fork in a symmetrical arrangement, such that each of the two legs of the cantilever is fixed to one of the prongs of the tuning fork. The tuning fork is used as an oscillatory force sensor. Its frequency and amplitude governs that of the vibrating tip, while the cantilever determines the spring constant of the whole probe. Several probes with different cantilevers in terms of material and spring constant are studied. A typical silicon nitride cantilever has a spring constant of 0.1 N/m and those made of silicon have 1.2-319 N/m. Monoatomic terraces of highly oriented pyrolytic graphite (HOPG) was successfully imaged in the intermittent contact mode with the silicon probes. Both types of probes are suited for batch fabrication and assembling and, therefore enlarges the applications of the tuning fork based AFM. © 2002 Elsevier Science B.V. All rights reserved.

The fabrication of silicon cantilever-based scanning near-field optical microscope probes with fully aluminium-coated quartz tips was optimized to increase production yield. Different cantilever designs for dynamic- and contact-mode force feedback were implemented. Light transmission through the tips was investigated experimentally in terms of the metal coating and the tip cone-angle. We found that transmittance varies with the skin depth of the metal coating and is inverse to the cone angle, meaning that slender tips showed higher transmission. Near-field optical images of individual fluorescing molecules showed a resolution < 100 nm. Scanning electron microscopy images of tips before and after scanning near-field optical microscope imaging, and transmission electron microscopy analysis of tips before and after illumination, together with measurements performed with a miniaturized thermocouple showed no evidence of mechanical defect or orifice formation by thermal effects.

A process for batch fabricating and mounting polymer (SU-8, EPON) tips on a mass-produced quartz tuning fork wafer is proposed in this paper. In order to add a sharp tip to a side wall of such tuning forks, three unconventional procedures were combined with an optical lithography step: (1) gluing the sample and mask together; (2) coating a photosensitive polymer directly on this ensemble; and (3) inclining the mask during exposure. Sharp SU-8 tips with a 170 nm radius of curvature were obtained. These tuning fork sensors were successfully applied in scanning force microscope imaging in the dynamic mode.

In this article an integrated force sensor based on a stress-sensing MOS transistor is introduced for applications in scanning force microscopy (SFM) . The sensor configuration will be described, and theoretical and experimental investigations of the sensitivity will be presented. With the fabrication process, consisting of a standard CMOS process and post-processing (conventional silicon bulk micromachining), cantilevers with MOS transistors integrated at the base for deflection detection have been fabricated. The cantilevers typically have a spring constant of 1 N m-1, are 400 to 950 um in length and have a mechanical resonance frequency between 6.2 and 35 kHz. It is found that the stress sensitivity of the MOS transistor changes with the gate voltage, while being independent of the drain voltage. The cantilevers have successfully been used for SFM imaging in both contact mode and dynamic mode (tapping mode). These cantilevers together with integrated circuits are expected to be well suited for mass production because of their CMOS processing compatibility.

The self-assembling of three-dimensional (3-D) MEMS from polysilicon surface micromachined part is very attractive. To avoid risky external manipulation, the practical use of integrated actuator to perform the assembling task is required. To that goal, this paper presents detailed characteristics of the electrostatic surface micromachined scratch drive actuator (SDA). First, from numerous SDA tests, it is shown that this actuator is able to produce a threshold force of 30 /spl mu/N, with a yield above 60%. With polysilicon devices consisting of SDA mechanically linked to buckling beam, a horizontal force of 63 mN has been demonstrated with /spl plusmn/112 V pulse, and up to 100 /spl mu/N can be obtained with higher voltage. With buckling beams, displacements up to 150 /spl mu/m have been obtained in the vertical direction. The generation of vertical force of 10 /spl mu/N was confirmed with a 100 /spl mu/m displacement producing 1 nJ work in the vertical direction. Finally, SDA overcomes the usual sticking of surface machined polysilicon by producing enough vertical force to completely release wide polysilicon plate (500 /spl mu/m/spl times/50 /spl mu/m) without external manipulation. The above characteristic, both in terms of structure releasing and vertical/horizontal forces and displacements provides the SDA with the capability of self-assembling complex 3-D polysilicon part, opening new integration capabilities and new application field of MEMS.

This paper presents a new reshaping technology which is suitable to realize real three dimensional silicon microstructures. In this process, the elastically deformed polysilicon structure is annealed by Joule heating generated by the current passing through the structure. Plastic deformation occurs resulting in permanent three dimensional shapes. The application of this basic process to different polysilicon structures is successfully performed. Some quantitative characteristics of the annealing effects are also investigated by means of structure deformation measurements.

The nanomechanical properties of cancerous cells are of great interest to understand how a localized tumor becomes metastatic. We present a 2D cantilever array to investigate the stiffness and adhesion characteristics of multiple cells at a high throughput. A new molding process based on thermal oxidation of silicon allows us to create at a wafer scale spherical tips with a radius of curvature of 3.8 μm. Simulations show that radii ranging from 2.5 μm to 6.5 μm can be produced. The customized cantilever array system was used to simultaneously probe 13 melanoma living cells (WM239). The Young's moduli of the cells were successfully obtained with the Hertz model.

Platinum TSVs compatible with harsh-environment post-processing were fabricated on an SOI wafer. This study was part of a larger project for the development of a SWCNT resonator, 3D-integrated, in a “via-first” approach, with its driving electronics. After their passivation, they are compatible with the harsh-environment post-processes necessary for the fabrication of the SWCNT resonator: the growth of CNT at a high temperature of 850 °C in an oxidizing environment, and their release in concentrated HF solution. The TSV metallization formed a stable ohmic contact with the silicon device layer on which the CNT resonator will be standing. We present RF (radio frequency) simulations correlated with RF measurements of the Pt-TSVs from 0.3 to 5 GHz. A reflection coefficient of -20 dB and transmission coefficient of -4 dB were measured at 5 GHz.

Microfabricated instruments featuring functional elements at the nanometre scale are ideally suited to interrogate and manipulate objects in the small domain. This ability would also be attractive and open new opportunities for industrial applications. However, robustness of the instrument and their currently low throughput are considered as almost insurmountable obstacles for a successful implementation in many commercial fields. Here, scientific instrumentation in harsh, demanding environments can play a pivotal role in validating the concept and demonstrating the reliability of the instrument. This is highlighted in two examples, one in medicine and one in planetary science.

In this contribution we present a scanning probe with a gold-tip completely encapsulated with insulator all the way to the apex. The probe fabrication is unique owing to an in-plane arrangement in which the width of the cantilever is defined by deep reactive ion etching (DRIE). E-beam lithography was employed for defining the gold nanowire tip. The cantilever and the chip body were defined by DRIE in later steps. The radius of curvature of the tip apex is around 20 nm. The high-quality insulation on the tip was demonstrated by performing electrodeposition of gold. The spring constant of the cantilever was obtained by measuring the resonance frequency of the cantilever. With this in-plane fabrication process, probes with different spring constants ranging from 0.1 N/m to 9 N/m were fabricated on the same wafer.

We present the fabrication, characterization and successful medical application of a membrane-type surface stress sensor (MSS), arranged in arrays for molecular detection in gaseous phase. Made out of SOI substrate, a round membrane with a diameter of 5 0 0 mu m and a thickness of 2.5 mu m is suspended by four sensing beams with integrated p-type piezoresistors, composing a full Wheatstone bridge. The membrane is coated with a thin polymer layer, which reacts with volatile molecules and produces a deflection of the membrane. The membranes were functionalized with various polymers and characterized as humidity sensors with a sensitivity of 87 mV/%RH and a time constant (Tau63%) of 1.3 s. Finally, through breath analysis and the use of principal component analysis (PCA), we were able, in a double blind trial, to distinguish cancer patients and healthy persons.

We have recently demonstrated that indentation-type atomic force microscopy (IT-AFM) is capable of detecting early onset osteoarthritis (OA) (Stolz, 2009). This study was based on biopsies, using a desk-top commercial atomic force microscope (AFM). However, cartilage analysis in the knee joints needs to be non-destructive to avoid new seeding points for OA by the taking of biopsies. This requires bringing the probe tip in contact with the articular cartilage (AC) surface inside the joint. Here we present our recent progress towards a medical instrument for performing such IT-AFM measurements for in-vivo knee diagnostics. The scanning force arthroscope (SFA) integrates a miniaturized AFM into a standard arthroscopic sleeve, and is used for direct, quantitative, in situ inspection of AC (Imer et al., 2006). The stabilization and the positioning of the instrument relative to the surface under investigation were performed by means of eight inflatable balloons. An integrated three-dimensional, piezoelectric scanner allowed raster scanning and probing of a small area of cartilage around the point of insertion. An AFM probe with an integrated deflection sensor was mounted at the distal end of the instrument. Using this instrument, several measurements were performed on agarose gel and on porcine cartilage samples. The load-displacement curves obtained were analyzed and the dynamic elastic moduli vertical bar E*vertical bar were calculated. A good correlation between these values and those published in the scientific literature was found. Therefore, we concluded that the SFA can provide quantitative measurements to detect early pathological changes in OA.

Nanomechanical cantilever sensors have been emerging as a key device for real-time and label-free detection of various analytes ranging from gaseous to biological molecules. The major sensing principle is based on the analyte-induced surface stress, which makes a cantilever bend. In this letter, we present a membrane-type surface stress sensor (MSS), which is based on the piezoresistive read-out integrated in the sensor chip. The MSS is not a simple "cantilever," rather it consists of an "adsorbate membrane" suspended by four piezoresistive "sensing beams," composing a full Wheatstone bridge. The whole analyte-induced isotropic surface stress on the membrane is efficiently transduced to the piezoresistive beams as an amplified uniaxial stress. Evaluation of a prototype MSS used in the present experiments demonstrates a high sensitivity which is comparable with that of optical methods and a factor of more than 20 higher than that obtained with a standard piezoresistive cantilever. The finite element analyses indicate that changing dimensions of the membrane and beams can substantially increase the sensitivity further. Given the various conveniences and advantages of the integrated piezoresistive read-out, this platform is expected to open a new era of surface stress-based sensing.

This paper presents a polysilicon slider and a rotor capable of stepwise motion. These devices were fabricated on a silicon wafer with surface micromachine technology. The proportional relation between the velocity of motion and the frequency of the applied pulse was experimentally confirmed. The peak value of the applied pulse determines the step length. The step values observed were in the range of 10-30 nm for a bushing height of 1.0 mu m and of 40-80 nm for a bushing height of 2.0 mu m depending on the peak voltage of the applied pulse. >

We report about the development of a planar support for biological samples. The aim is to combine AFM and patch-clamp measurements, in order to perform simultaneous measurements of topography and electrical properties of biological membranes. Sub-micrometer apertures have been fabricated using standard MEMS techniques. The electrical quality of the support has been experimentally assessed.

Batch-fabricated conductive cantilevers that are merely insulated except for a small part at the tip, enable combination of atomic force microscopy and scanning electrochemical microscopy. This allows correlation of topographical features with a lateral, resolution of about 1 nm and functional features at a resolution

A combined atomic force and scanning electrochemical microscope probe is presented. The probe is electrically insulated except at the very apex of the tip, which has a radius of curvature in the range of 10-15 nm. Steady-state cyclic voltammetry measurements for the reduction of Ru(NH3)6Cl3 and feedback experiments showed a distinct and reproducible response of the electrode. These experimental results agreed with finite element simulations for the corresponding diffusion process. Sequentially topographical and electrochemical studies of Pt lines deposited onto Si3N4 and spaced 100 nm apart (edge to edge) showed a lateral electrochemical resolution of 10 nm.

This paper presents a new basic reshaping technology which is efficient to realize real three dimensional silicon microstructures. In this process, the elastically deformed polysilicon structure is annealed by Joule heating generated by the current passing through the structure. Plastic deformation occurs resulting in permanent three-dimensional shapes. The application of this basic process to different polysilicon structures is successfully performed. Some quantitative characteristics of the annealing effects are also investigated by means of structure deformation measurements.

We have presented a design of silicon cantilever based scanning near-field optical microscopy (SNOM) probes with aluminum coated quartz tips which have been batch fabricated using micromachining technology. The 12 /spl mu/m high probe tips are made of SiO/sub 2/ and fabricated at the end of silicon cantilevers. A hole in the cantilever, located underneath the tip base, permits light insertion and collection through the cantilever. Transmission electron microscopy reveals a 60 nm thick polycrystalline aluminum layer that covers the tip entirely. Still, far-field measurements show the typical polarization properties of conventional SNOM aperture probes. In order to study the mechanism of light transmission through such a tip, theoretical modelling and several experiments were performed.

In this paper, we report about the development of this multifunctional AFM probe. This insulated conductive probes to measure the topography of biological membranes.

The atomic force microscope (AFM) allows biomolecules to be observed and manipulated under native conditions. It operates in buffer solution, produces molecular images with outstanding signal-to-noise ratio, and addresses single molecules. Progress in sample preparation and instrumentation has led to topographs that reveal sub-nanometer details and surface dynamics of biomolecules. Antibodies or oligonucleotides immobilized on cantilevers induce bending upon binding of the cognate biomolecule, allowing sub-picomolar concentrations to be measured. Biomolecules tethered between support and retracting AFM-tip produce force extension curves that reflect the mechanical stability of secondary structure elements. Furthermore, multifunctional tips may activate single molecules to observe them at work. In all cases, the cantilever is critical: its mechanical properties dictate the force-sensitivity and the scanning speed.

In spite of the considerable progress achieved in fabricating scanning near-field optical microscopy (SNOM) probes, the process to prepare smooth tip surfaces with aperture sizes under 100 nm is still expensive and time consuming. Recently, silicon cantilever-based SNOM probes with aluminum-coated quartz (fused silica) tips have been batch fabricated using micro machining technology. The tip apex is fully covered with a metal layer in the range of 60 nm thickness. It is the objective of this work to theoretically and experimentally elucidate the mechanism responsible for the light transmission through these novel probes.

We present a self‐actuating and self‐sensing probe, with an electrically connected, monolithic tip for dynamic AFM. It is based on a quartz tuning fork and a microfabricated cantilever. The tuning fork — cantilever assembly opens a new avenue for electrically contacting the tip in a reproducible way. Such a probe can be used for scanned gate microscopy and for atomic force probers. Since the probe is self‐sensing, the probe can be used in environments where optical readout is not possible. Our probes allows for batch fabrication and assembly.

Polysilicon sliders and rotors with a new step motion, which are fabricated on a silicon wafer by surface micromachine technology, are presented. The proportional relation between the velocity and the applied pulse frequency is experimentally confirmed. The coefficient in the relation is the step for an applied pulse, which is determined by the peak voltage of applied pulse, bushing height plate length, plate thickness etc. >

In this article an integrated force sensor based on a stress-sensing MOS transistor is introduced for applications in scanning force microscopy (SFM). The sensor configuration will be described, and theoretical and experimental investigations of the sensitivity will be presented. With the fabrication process, consisting of a standard CMOS-process and post-processing (conventional silicon bulk micromachining), cantilevers with MOS transistors integrated at the base for deflection detection were fabricated. Furthermore, Pt-tips were grown on some of the cantilevers by using focused ion beam (FIB) deposition techniques. The cantilevers have typically a spring constant of 1 N/m, and are 400 to 950 /spl mu/m in length, and have a mechanical resonance frequency between 6.2 and 35 kHz. It was found that the stress sensitivity of the MOS transistor changed depending on gate voltage, while being independent of the drain voltage. The cantilevers were successfully used for SFM-imaging in contact-mode. The resolution is noise limited to a few nanometer in the contact-mode, while atomic resolution is expected to be feasible in the dynamic-mode. These cantilevers together with integrated circuits are expected to be well suited for mass production because of their CMOS processing compatibility.

This paper presents an X/Y stage actuated by scratch drive actuators (SDA) and processed by silicon surface machining. First a quantitative SDA analysis for X/Y motion is presented. The minimum step motion produced by the SDA have been measured as small as 25 nm. Then, feasibility of using SDA for motion of X/Y stage is established. A maximum displacement of 50 /spl mu/m along X-axis and 40 /spl mu/m along Y-axis has been demonstrated.