G. Gurley

Bio: G. Gurley is an academic researcher. The author has contributed to research in topics: Non-contact atomic force microscopy & Atomic force acoustic microscopy. The author has an hindex of 6, co-authored 6 publications receiving 750 citations.

Short cantilevers for atomic force microscopy

Abstract: We have designed and tested a family of silicon nitride cantilevers ranging in length from 23 to 203 μm. For each, we measured the frequency spectrum of thermal motion in air and water. Spring constants derived from thermal motion data agreed fairly well with the added mass method; these and the resonant frequencies showed the expected increase with decreasing cantilever length. The effective cantilever density (calculated from the resonant frequencies) was 5.0 g/cm3, substantially affected by the mass of the reflective gold coating. In water, resonant frequencies were 2 to 5 times lower and damping was 9 to 24 times higher than in air. Thermal motion at the resonant frequency, a measure of noise in tapping mode atomic force microscopy, decreased about two orders of magnitude from the longest to the shortest cantilever. The advantages of the high resonant frequency and low noise of a short (30 μm) cantilever were demonstrated in tapping mode imaging of a protein sample in buffer. Low‐noise images were tak...

Recent advances in atomic force microscopy of DNA.

Abstract: Three advances involving DNA in atomic force microscopy (AFM) are reported here. First a HEPES-Mg buffer has been used that improves the spreading of DNA and provides good DNA coverage with as little as 200-500 picograms per sample. Second, the new "tapping" mode has been used to improve the ease and resolution of AFM-imaging of DNA in air. Finally, AFM images are presented of single-stranded phi X-174 virion DNA with the gene 32 single-stranded binding protein. A summary of the current state of the field and of the methods for preparing and imaging DNA in the AFM is also presented.

A new, optical‐lever based atomic force microscope

Abstract: A new optical‐lever based atomic force microscope is described in which the cantilever scans and is accurately tracked by a scanning focused spot. It can operate at forces below one nanoNewton over image areas greater than 100 μ×100 μ. It can be combined with optical microscopes of high numerical aperture and operated with the sample and cantilever in fluids. As examples of its applications, images of living cells in Petri dishes and a 6 in. (15.24 mm) silicon wafer are included.

Atomic force microscopy using small cantilevers

Abstract: We have applied a new generation of short cantilevers with high resonant frequencies to tapping mode atomic force microscopy of a process in situ. Crystal growth in the presence of protein has been imaged stably at 79 lines/s (1.6 s/image), using a 26 micrometers long cantilever with a spring constant of 0.66 N/m at a tapping frequency of 90.9 kHz. This high scan speed nearly eliminated distortion in the step edge motion and allowed imaging of finer features along the step edges. Atomic force microscopy with short cantilevers therefore allows higher resolution imaging of crystal growth in space as well as time.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Bent-fiber near-field scanning optical microscopy probes for use with commercial atomic force microscopes

Abstract: The adaptation of a Digital Instruments DimensionTM 3000 atomic-force microscope to provide a near-field scanning optical microscopy capability is described. The enabling technology for the adaptation is the bent optical fiber probe. The design and operation of this probe to measure evanescent fields emerging from optical waveguides is described.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Calibration of rectangular atomic force microscope cantilevers

Abstract: A method to determine the spring constant of a rectangular atomic force microscope cantilever is proposed that relies solely on the measurement of the resonant frequency and quality factor of the cantilever in fluid (typically air), and knowledge of its plan view dimensions. This method gives very good accuracy and improves upon the previous formulation by Sader et al. [Rev. Sci. Instrum. 66, 3789 (1995)] which, unlike the present method, requires knowledge of both the cantilever density and thickness.

Frequency response of cantilever beams immersed in viscous fluids with applications to the atomic force microscope

Abstract: The vibrational characteristics of a cantilever beam are well known to strongly depend on the fluid in which the beam is immersed. In this paper, we present a detailed theoretical analysis of the frequency response of a cantilever beam, that is immersed in a viscous fluid and excited by an arbitrary driving force. Due to its practical importance in application to the atomic force microscope (AFM), we consider in detail the special case of a cantilever beam that is excited by a thermal driving force. This will incorporate the presentation of explicit analytical formulae and numerical results, which will be of value to the users and designers of AFM cantilever beams.

Cantilever transducers as a platform for chemical and biological sensors

Abstract: Since the late 1980s there have been spectacular developments in micromechanical or microelectro-mechanical (MEMS) systems which have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged. In this article, we discuss sensors with transducers in a form of cantilevers. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. The review deals with four important aspects of cantilever transducers: (i) operation principles and models; (ii) microfabrication; (iii) figures of merit; and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors.

A high-speed atomic force microscope for studying biological macromolecules.

Abstract: The atomic force microscope (AFM) is a powerful tool for imaging individual biological molecules attached to a substrate and placed in aqueous solution. At present, however, it is limited by the speed at which it can successively record highly resolved images. We sought to increase markedly the scan speed of the AFM, so that in the future it can be used to study the dynamic behavior of biomolecules. For this purpose, we have developed a high-speed scanner, free of resonant vibrations up to 60 kHz, small cantilevers with high resonance frequencies (450–650 kHz) and small spring constants (150–280 pN/nm), an objective-lens type of deflection detection device, and several electronic devices of wide bandwidth. Integration of these various devices has produced an AFM that can capture a 100 × 100 pixel2 image within 80 ms and therefore can generate a movie consisting of many successive images (80-ms intervals) of a sample in aqueous solution. This is demonstrated by imaging myosin V molecules moving on mica (see http://www.s.kanazawa-u.ac.jp/phys/biophys/bmv_movie.htm).