A novel optical waveguide microcantilever sensor for the detection of nanomechanical forces

The authors present the fabrication and characterization of an integrated optical readout scheme based on single-mode waveguides for cantilever-based sensors. The cantilever bending is read out by monitoring changes in the optical intensity of light transmitted through the cantilever that also acts as a waveguide. The complete system is fabricated in the photosensitive polymer SU-8. They show theoretical calculations on the expected sensitivity both when operated in air and liquid and compare these with experimental characterization of the system in air where the cantilever is deflected mechanically. The experimental results compare well with the results obtained from the theoretical calculations.

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confidence: 95%

Integrated optical readout for miniaturization of cantilever-based sensor system

Nordström

Zauner

Calleja³

et al. 2007

“…The device was fabricated using the technology reported elsewhere. 9 The waveguide microcantilever made of silicon dioxide is an extension of the silicon dioxide layer thermally grown on silicon substrate. The developed technology allowed fabrication of stress-free silicon dioxide cantilevers.…”

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confidence: 99%

“…The light propagates until the end of the cantilever and couples into the output waveguide separated from the cantilever by a short gap of 3 m. The coupling efficiency to the output waveguide is a function of the cantilever deflection. 9 The cantilever beam is 600 nm thick, 200 m long, and 40 m wide; the cantilever fundamental resonance mode can be excited at frequency of about 13 kHz. 9 The cantilever waveguide supports two propagating modes for the light wavelength of 633 nm.…”

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confidence: 99%

“…9 The cantilever beam is 600 nm thick, 200 m long, and 40 m wide; the cantilever fundamental resonance mode can be excited at frequency of about 13 kHz. 9 The cantilever waveguide supports two propagating modes for the light wavelength of 633 nm. A gold layer with thickness of ϳ10 nm was deposited on the bottom surface of the cantilever using the electron beam sputtering.…”

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confidence: 99%

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Optical waveguide cantilever actuated by light

Zinoviev

Domı́nguez

Plaza

et al. 2008

We present experimental studies and theoretical analysis of a microcantilever working as an optical waveguide metallized from one side and actuated by light propagating inside it. Light absorbed in the metallic layer increases the temperature of the bimetallic structure and induces the cantilever bending. Dynamical properties of the cantilevers were studied using actuation by light modulated at frequencies of up to 800 Hz. The deflection of the cantilever by 400 nm was obtained while 0.25 mW of light power was coupled inside it.

“…1,5 Recently, it was shown that motion of micron-scale devices can be monitored through changes in end-to-end alignment of optical waveguides. [9][10][11] In this letter, we propose an integrated and near-field optical motion detection technique that exploits near-field optical evanescent-wave coupling. We demonstrate that the technique works efficiently for nanoscale mechanical resonators, with greater sensitivity than conventional optical techniques.…”

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confidence: 99%

Detection of nanomechanical motion by evanescent light wave coupling

Vlaminck

Roels

Taillaert

et al. 2007

The authors demonstrate a technique allowing sensitive nanomechanical motion detection based on the evanescent light wave coupling between two photonic nanowires. Any relative motion between the nanowires results in a change in light coupling, providing a means of registering motion. The in-plane vibrations of a 220 nmϫ 400 nmϫ 10 m nanomechanical resonator were recorded using this method. An analysis of the sensitivity reveals the potential of this integrated technique to provide fast and sensitive motion detection. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2746067͔ Nanoelectromechanical systems ͑NEMSs͒ have received great attention in recent years. Most research has focused on resonant devices for sensor applications. 1,2 Through scaling of the mechanical sensing element from the micron-to the nanoscale, researchers were able to improve the detection limits in force and mass sensing drastically. Devices sensitive enough to measure the magnetic moment of a single electron spin 3 or to perform zeptogram scale mass sensing 4 have resulted from efforts in scaling. A central problem in the development of even more sensitive mechanical sensors is the fast and high-precision detection of motion. In many cases, the performance of the sensor is restricted by the efficiency of the motion detection method employed, more so than by the inherent capabilities of the mechanical element. Much research has been devoted to solving this problem and a myriad of optical and electronic techniques has been developed. 5 Optical motion detection techniques have the inherent advantage that optical signals can be communicated with very large bandwidth. 6-8 Unfortunately, for conventional optical techniques, diffraction effects limit the attainable detection limits when the mechanical devices are scaled. It has been anticipated that these issues can be overcome by integration of mechanical sensors with nanophotonics and by exploiting optical near-field effects. 1,5 Recently, it was shown that motion of micron-scale devices can be monitored through changes in end-to-end alignment of optical waveguides. [9][10][11] In this letter, we propose an integrated and near-field optical motion detection technique that exploits near-field optical evanescent-wave coupling. We demonstrate that the technique works efficiently for nanoscale mechanical resonators, with greater sensitivity than conventional optical techniques.The approach offers potential for applications where robust and sensitive measurement of motion is required and applications requiring remote detection or detection of motion in harsh environments. The integration of the device with photonic circuitry reduces the complexity of addressing large arrays of devices.The detection of nanomechanical motion is achieved through the near-field coupling of light from a photonic waveguide to a mechanical resonator. The mechanical resonator acts as a photonic waveguide; when the evanescent tails of the guided modes of the resonator and waveguide overlap, photons tunnel from one wavegu...