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Heated microcantilevers sensors

Heated microcantilevers sensors. Heated microcantilever. Microcantilever with CNT sensing layers. IR image of the cantilever.

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Heated microcantilevers sensors

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  1. Heated microcantilevers sensors Heated microcantilever Microcantilever with CNT sensing layers IR image of the cantilever The heated cantilever can be used as an excellent sensor for (i) chemical analysis of trapped molecules in the CNT layers, (ii) measuring thermal properties of surrounding gases, and (iii) various SPM probing methods, including lithography

  2. Noise in piezoresistive microcantilever • Electrical noise • Johnson noise (Random thermal motion of carriers) • 1/f low frequency noise (Carrier mobility fluctuation due to bulk defects or carrier number fluctuation due to surface traps) • Vibration noise • Thermo-mechanical noise (Random movement of molecular in air surrounding mechanical structures leads to random fluctuations in the energy transfer between structure and damping gas)

  3. Electrical noise Johnson noise SV: Noise power spectrum density kB:Boltzmann's constant T : Temperature R : Resistance R = 1100 Ω Measurement bandwidth Δf = 1 Hz Deflection sensitivity = 11e-5 per µm, Vbias = 1.0 V RMS noise JOHNSON = 0.03 nm

  4. Electrical noise 1/f low frequency noise (Flicker noise) SV : noise power spectral density [V2/Hz] N : the number of carriers (depends on the piezoresistor volume and implant dose) Vbias : bias voltage , f : the frequency, n: unity (n=1) α: empirical coefficient depends on annealing length: fmax= 100 Hz fmin= 1 Hz R = 99.2 Ω Lr = 54 µm Wr = 14 µm Hr = 2 µm Vbias = 1 V µ = 400 cm2/Vs kBT = 0.026 eV α=1.0e-6

  5. Vibration noise Thermo-mechanical noise L=250 µm W=140 µm H=2 µm E = 179GPa Q = 69 w0 = 2*pi* 31.5 kHz KBT = 0.026 eV k= 3.11N/m B = 1 Hz Force noise spectrum density At resonance: RMS noise TM = 0.0013 nm At resonance, Vac = 5.0 sin (ωt) Minimum Δφ = 12 μV P. G. Datskos, N. V. Lavrik, and S. Rajic, “Performance of uncooled microcantilever thermal detectors”, Rev. Sci. Intr., 75, 1134 (2004)

  6. Nanowire based chemical sensing InN/In2O3 nano core/shell based FET sensor Morphology Probe current SEM image TEM image Diffraction pattern µ = 150 cm2/Vs J. Liu, Z. Cai, G. Koley, “Charge transport and trapping in InN nanowires investigated by scanning probe microscopy”, J. Appl. Phys. 106, 124907 (2009)

  7. In2O3 shell layer InN core …Continued TEM image of nano core/shell InN/In2O3 NWs SEM image of NanoFET Vth shifted NO2 sensing 45 ppb (parts-per-billion) NO2 could be detected

  8. TMV nanofiber based sensor TEM image of TMV nanofibers Conductivity σ = 2.93 x10-5Ω-1cm-1 Z. Niu, J. Liu, L. A. Lee, M. A. Bruckman, D. Zhao, G. Koley, Q. Wang, “Biological Templated Synthesis of Water-Soluble Conductive Polymeric Nanowires”, Nano Lett. 7, 3729 (2007)

  9. …Continued Off Methanol On Time (s) Good selectivity toward Methanol and Ethanol vapor M. A. Bruckman, J. Liu, G. Koley, Y. Li, B. Benicewicz, Z. Niu, and Q. Wang, “Tobacco mosaic virus based thin film sensor for detection of volatile organic compounds”, J. Mater. Chem. 20, 5715 (2010)

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