Hall devices having an active area of about ͑500 nm͒ 2 are fabricated by focused electron-beam-induced deposition. The deposited material consists of cobalt nanoparticles in a carbonaceous matrix. The realized devices have, at room temperature, a current sensitivity of about 1 V / AT, a resistance of a few kilo-ohms, and can be biased with a maximum current of about 1 mA. The room-temperature magnetic field resolution is about 10 T/Hz 1/2 at frequencies above 1 kHz. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1856134͔Magnetic sensors having submicrometer spatial resolution are key elements in several fundamental studies as well as industrial applications.1-4 Hall effect devices are emerging as one of the most suitable solutions. [4][5][6][7][8][9] The ordinary Hall effect is due to the Lorentz force acting on charge carriers in metals, semi-metals, and semiconductors.5 Magnetic materials show additional "Hall phenomena" which are, generally speaking, generated by spin-orbit interactions: the so-called extraordinary [10][11][12][13][14][15][16] and planar Hall effects. 17-20The local deposition of materials using a focused electron beam in the presence of a volatile precursor is a wellestablished technique for the maskless fabrication of submicrometer structures such as functionalized tips for scanning probe microscopy, 21-26 electrodes for local conductivity measurements, 27 solder bonds for carbon nanotubes studies, 28 nanowires, 29-33 and nanodots. 34 In this letter we demonstrate the possibility to grow highly sensitive cobaltcarbon submicrometer Hall devices by means of a focused electron beam. This flexible "single-step" process represents an alternative to the conventional "multisteps" methods, which are usually based on a combination of optical ͑or electron beam͒ lithography and focused ion beam milling. The realized devices show a strong extraordinary Hall effect, whereas the ordinary and planar Hall effects ͑in most of the devices͒ are relatively small.

Sequential position readout from a microfabricated array of eight cantilever-type sensors ͑silicon technology͒ is demonstrated. In comparison with single sensors we find that mechanical disturbances from noise, such as from vibrations, turbulent gas flow, or abrupt pressure changes, can be effectively removed in array sensors by recording difference signals with respect to reference cantilevers. We demonstrate that chemically specific responses can be extracted in a noisy environment using a sensor to detect specific chemical interactions and an uncoated cantilever as reference.

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A new probe made entirely of plastic material has been developed for scanning probe microscopy. Using a polymer for the cantilever facilitates the realization of mechanical properties that are difficult to achieve with classical silicon technology. The new cantilever and tip presented here are made of an epoxy-based photoplastic. The fabrication process is a simple batch process in which the integrated tip and the lever are defined in one photolithography step. The simplicity of the fabrication step, the use of a polymer as material, and the ability to reuse the silicon mold lead to a soft low-cost probe for scanning force microscopy. Imaging soft condensed matter with photoplastic levers, which uses laser beam deflection sensing, exhibits a resolution that compares well with that of commercially available silicon cantilevers.

Abstract.We have built and operated a novel setup for the characterization and identification of gases or vapors based on sequential position readout via a beam-deflection technique from a microfabricated array of eight cantilever-type sensors. Each of the cantilevers can be coated on one side with a different sensor material to detect specific chemical interactions. We demonstrate that disturbances from vibrations and turbulent gas flow can be effectively removed in array sensors by taking difference signals with reference cantilevers. For example, H 2 can be detected by its adsorption on a Pt-coated sensor because a change in surface stress causes a static bending of the sensor. The diffusion of various alcohols into polymethylmethacrylate induces resonance frequency shifts in a dynamic measuring mode and bending in the static mode, which allows one to distinguish between the various alcohols.Sensor devices for detection of gases and vapors via specific coatings are gradually gaining importance in chemistry, materials science, and biochemistry owing to the increasing demand for detection of analytes at monolayer coverage.