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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3434-3439 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The feasibility of microcantilever-based optical detection is demonstrated. Microcantilevers may provide a simple means for developing single-element and multielement infrared sensors that are smaller, more sensitive, and lower in cost than quantum well, thermoelectric, or bolometric sensors. Here we specifically report here on an evaluation of laboratory prototypes that are based on commercially available microcantilevers, such as those used in atomic force microscopy. In this work, optical transduction techniques were used to measure microcantilever response to remote sources of thermal energy. The noise equivalent power at 20 Hz for room temperature microcantilevers was found to be approximately 3.5 nW/(square root of)Hz, with a specific detectivity of 3.6×107 cm Hz1/2/W, when an uncoated microcantilever was irradiated by a low-power diode laser operating at 786 nm. Operation is shown to be possible from dc to kHz frequencies, and the effect of cantilever shape and the role of absorptive coatings are discussed. Finally, spectral response in the midinfrared is evaluated using both coated and uncoated microcantilevers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3662-3667 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The advent of inexpensive, mass-produced microcantilevers promises to bring about a revolution in the field of chemical and physical sensor design. In this paper, a novel class of highly sensitive sensors are discussed that are based on commercially available microcantilevers, such as those used in atomic force microscopy. When coated with a sensitizing overlayer, these microcantilevers show significant changes in two independent analyte-induced signals, resonance frequency and static bending, as the result of exposure to various chemical and physical phenomena. Resonance frequency shift has the particular advantage of being relatively insensitive to interference from external factors such as thermal drift. Examples of micromechanical sensors based on this approach that are capable of detecting mercury vapor (with a sensitivity of 1.25 Hz/pg and linear correlation of 0.998), relative humidity (55 Hz/%R.H., correlation=0.999), or optical irradiation (10 Hz/nJ response) are discussed in detail, along with the effects of coatings on sensitivity, linearity, and reversibility of response. Further, extension of this tremendously flexible concept into a universal detection paradigm for chemical and physical phenomena is examined. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3618-3622 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is well known that bimetallic microcantilevers can exhibit static deflection as a result of thermal effects, including exothermic adsorption of chemicals on their surfaces. It is shown here that the resonance frequency of a cantilever can change due to a combination of mass loading and change of spring constant resulting from adsorption of chemicals on the surface. Cantilevers also undergo static bending that is induced by differential surface stress. The magnitude of these effects depends upon the chemical properties of the surface and upon the amount of material adsorbed. Hence cantilever deflection as well as resonance frequency change can be used as the basis for development of novel chemical sensors. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2986-2988 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel micromechanical infrared (IR) radiation sensor has been developed using commercially available piezoresistive microcantilevers. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress between the top layer (coating) and the substrate. The bending causes a change in the piezoresistance and is proportional to the amount of heat absorbed. The microcantilever IR sensor exhibits two distinct thermal responses: a fast one (〈ms) and a slower one (∼10 ms). A noise equivalent power (at a modulation frequency of 30 Hz) was estimated to be ∼70 nW/Hz1/2. This value can be further reduced by designing microcantilevers with better thermal isolation that can allow microcantilevers to be used as uncooled IR radiation detectors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 806-810 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An architecturally simple yet versatile memory-state-based digital pulse generator (or state machine) has been developed for control of instrumentation with PC-compatible microcomputers. The pulse-programming device uses parallel memory allocation to allow simultaneous output-state and address change capabilities. The pulse sequence is loaded into parallel sections of resident memory as a program consisting of output states, state durations, and partial pointers to succeeding states. The complete pointers are generated by concatenation of these address bits with the outputs of duration and loop counters, making complex jumps and loops possible. Minimum event duration and timing resolution is limited only by memory access time; fast or slow memory can be selected based on individual needs. The memory used in the device described has access times of 120 ns, allowing clock rates as high as 8 MHz. The cost of this device is under $200.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2285-2289 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An enhanced state-machine pulse programmer has been developed for use in microcomputer-controlled instrumentation; the device uses TTL logic, and is capable of operation with a 100-MHz clock. A hybrid counter is utilized which restricts the high-frequency clock to a small portion of the whole device, thereby limiting overall demands on circuit performance. For the device, timing resolution is determined by the speed of the delay counter circuitry utilized, while minimum event duration is limited by access times of the static RAM used for program storage. The device reported here, which utilizes a 32-bit delay counter, and which has 32 kwords of 150-ns program memory, is capable of generating events with a duration between 150 ns and 42.9 s at a constant resolution of 10 ns; the maximum duration can be extended indefinitely if looping is utilized. The hardware cost of the device, which has 16 output lines, is under $400.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1695-1697 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Oscillating silicon nitride microcantilevers coated with a thin gold film have been used to detect mercury vapor in air. Cantilever resonance frequency changes due to surface mass loading as a result of adsorption of mercury vapor. Furthermore, cantilever bending is also altered due to changes in surface stress induced by mercury adsorption on the gold overlayer. Both of these phenomena can be used to quantitatively detect adsorbed vapors with picogram mass resolution. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1563-1565 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate the use of microcantilevers coated with ultraviolet cross-linking polymers as optical radiation dosimeters. Upon exposure to radiation, a treated cantilever bends due to stress and its resonance frequency increases due to stiffening. These phenomena can be used to develop sensitive radiation dosimeters which respond to radiation affecting the mechanical properties of the selected coating.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 519-521 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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