A B S T R A C TA multifunctional sensor that responds to all -static/quasi-static or dynamic temperature or force -is reported. The sensor is based on a ferroelectric poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) capacitor connected to the gate of organic field-effect transistor (OFET). Both, the P(VDF-TrFE) capacitance and the output voltage of the P(VDF-TrFE)/OFET sensor exhibit a logarithmic response to static compressive force, leading to higher sensitivity for small forces. In addition, both the P(VDF-TrFE) capacitance and the output voltage of the P (VDF-TrFE)/OFET sensor exhibit a linear dependence on the static/constant temperature. Response to static force or temperature is observed irrespective of whether P(VDF-TrFE) is in ferroelectric or paraelectric states, confirming that piezo/pyroelectricity is not essential when monitoring static events. The piezo/pyroelectricity become activated during dynamic events (dynamic force or temperature) when the ferroelectric P(VDF-TrFE)/ OFET sensor is used. The obtained results indicate different sensing mechanisms for static and dynamic stimuli. Consequently, by choosing P(VDF-TrFE) layers in ferroelectric or paraelectric states a route for differentiating between the static and dynamic stimuli may exist.
Raman spectroscopy with subwavelength spatial resolution of a diamond sample was recorded using a tapered fiber optical probe in conjunction with a conventional Raman spectrometer. The experiment demonstrates the potential of suboptical wavelength resolution analytical spectroscopy. The tapered fiber optical probe with an aperture of around 100 nm, served as the means for delivering pump radiation while simultaneously collecting the Stokes radiation from the diamond specimen. Comparing the magnitude of the Raman scattering measured with the submicron single mode fiber probe to similar signals obtained with a nontapered probe made of the same type of fiber, illustrates the potential increase in effective optical aperture resulting from the close approach of the fiber to the surface.
The values of Young's modulus and internal stress in boron doped silicon microresonators fabricated by anisotropic etching techniques are reported. An array of resonators has been fabricated on a (100) orientation substrate and their resonant frequencies measured. Using the measured data, and equations relating the resonant frequencies to mechanical properties, the Young's modulus of the boron doped silicon is calculated to be 1.33*1011 Pa whilst the built-in stress is calculated to be 1.12*108 Pa.
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