Microcantilever sensors have been widely used in designing force, strain and biochemical sensors. The fast-growing applications in nanoelectromechanical systems (NEMS) lead to strong demands to downsize the sensing elements to nanometer scale. In this paper, the detected environment on the performance of this photonic crystal sensor is investigated. The nanocavity, which can be used to localize the electromagnetic field in a low refractive index region, is a new sensing method to measure nano-scaled deformation. Through numerical simulation, we demonstrate that the range of the force sensor in each component force in X and Y directions are 0-1μN. In X direction, the minimum detectable applied forces are about 0.057μN and 0.070μN for the microcantilever operated in the water and air, respectively. And these in Y direction are 0.043μN and 0.053μN, respectively. Hence, it shows that a better resolution of applied force can be achieved in water than in air.
With advantages of ultra-compact size, high resolution, and easy integration, nano-scaled force sensors based on photonic crystal are widely used in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS). The performances of these nano-scaled force sensors are mainly determined by the shape nanocavity. The principle of the sensor is that the output wavelength of the force sensor using photonic crystal varies as a function of force and pressure. In this work, a novel three dimensional nano-scaled force sensor based on silicon photonic crystal, in which a nanocavity is embedded in an S-shaped elastic body, is provided and studied numerically. The advantage of this force sensor is that it can be used in the NEMS to measure the component force in the X direction, Y direction and Z direction, simultaneously. The relationship between the force and the output wavelength is determined using finite element method (FEM) and finite difference time-domain method (FDTD).
As a kind of intelligent temperature-sensitive polymer, the poly (N-isopropylacrylamide) (PNIPA) hydrogel has lower
critical solution temperature (LCST) of 33°C. PNIPA could change from transparency to opacification due to its phase
separation. In this work, silicone coatings were doped with PNIPA particles, which were obtained by rotary cutting after
N-isopropylacrylamide cross link reaction between N-isopropylacrylamide and N, N-methylenebisacrylamide in the
aqueous solution below 20°C. The morphology and optical properties were characterized by SEM, FTIR and
UV-Vis-NIR, respectively. The results show that combination of silicone resin and PNIPA particles enhances the diffuse
reflection and operability in applications. It proves that the reversible thermal chronic property of PNIPA is useful for
intelligent thermal control application.
As an important index, the characterization of nano-materials' topography is directly related with their competitive ability
in micro-mechanical or information industries in which surface roughness and film's thickness play significant roles. With
the developments of semiconducting materials and devices, the requirements for testing instruments are been changing
from low accuracy, high accuracy to broad measuring range. To satisfy higher demands, the optical profiler method was
introduced with different working principle which is briefly described in this paper. As real samples of nano-materials,
such as multilayer films, their surface roughness and thickness were measured. In summary, this technique has excellent
performance in its fast, non-contact, accurate and repeatable features.