This paper presents a novel and effective characterization method for giant piezoresistive properties of silicon nanowires by using the reference structures. This contrast detection approach investigates the influences of quantum size effect and surface defects effect on piezoresistive coefficients of silicon nanowires by direct comparison of the resistivity change ratio of silicon wires with nanoscale-to-microscale width under the same applied stress conditions. The characterization experiments based on four-point bending tensile test demonstrate that piezoresistive coefficient of small nanowidth silicon nanowire can be significantly increased to about five times higher levels than that of bulk silicon under the same impurity concentration, which indicates that the silicon nanowire can have giant piezoresistive effect. On the other hand, to solve the problem on nanowires pick-up, we proposed a nanowire piezoresistive detection approach, whose validity is confirmed by the dynamic LDV resonance test. Meanwhile, to investigate the influence of undercut arising from the wet chemical release process of the suspended silicon nanowire, a three-dimensional finite element simulation is also carried out for the fundamental resonant frequency using ANSYS software. The numerical and experimental results show that our piezoresistive detection is accurate and effective and the undercut should be carefully considered in the design of the high frequency resonator and mixer. The findings of this paper provide some useful references for the piezoresistive effect measurement and the piezoresistive pick-up in nanoelectromechanical system.

A Lithium niobate (LiNbO3) based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer (MZI) and a tapered antenna has been designed and fabricated for measurement of pulsed E-field. Experimental results demonstrate that the minimum detectable E-field of the sensor is 10 kV/m. The linear relationship between the sensor input and output is better while the input E-fields varied from 10 kV/m to 370 kV/m. Besides, from the fitting curve it can be calculated that the maximum detectable E-field of the sensor is approximately equal to 1000 kV/m.

The size dependence becomes more significant as the devices scale down from micro-to nanodimensions, which is generally attributed to surface effects due to the very high surface-to-bulk ratios in nanoscale structures. However, significant discrepancies between experimental measurements and computational studies indicate that there could be other influences besides surface effects, such as the influences of native oxide layer, fabrication-induced defects and boundary conditions. In this paper, our purpose is to investigate mainly the influence of fabrication-induced defects on the elasticity of [110] silicon nanowires (SiNWs) with different cross sections. We accomplish this by using the molecular dynamics (MD) simulation. Our MD results show that the H-passivated [110] SiNWs without surface defects is slightly elastically softer than bulk, which is in good agreement with other literature MD values. However, the effective Young’s modulus of SiNWs with surface defects can significantly decreases as the defects increase. This softening behavior of [110] SiNWs is severe, which indicates the importance of surface defects. It is noted that the influence of defects on the Young's Modulus of SiNWs strongly depended on the distribution and morphology of defects as well as the cross-sectional shapes of SiNWs. It is observed that the influence of defects on square SiNWs is significantly different from those of hexagonal and triangle SiNWs. Our work reveals that fabrication-induced surface defects could be one of the important origins of the reduced effective Young’s modulus experimentally observed in ultra-thin SiNWs. Therefore, the effect of defects on the characterization of the mechanical properties of nanowire must be carefully considered.

This paper describes a hardware implementation of modular multiplication coprocessor for both RSA and ECC Cryptosystems. Using a self-improvement Montgomery modular multiplication algorithm, the coprocessor completes a modular multiplication with less clock cycles under the equivalent circumstance of the other designs. This modular multiplier can deal with variable operand lengths, from 128 to 2048. When adopting 64 bits multiplier, it can work at the frequency of 100MHz targeted to Virtex II XC2V250, and executes 256 bits EC point multiplication, with throughput 172k bit/s and 1024 bits RSA decryption(using CRT), with throughput 483k bit/s.

The dry bias of MEMS humidity sensor induced by solar radiation heating seriously affects the accuracy of the relative humidity (RH) measurement. To solve this problem, this paper presents a novel numerical analysis method for the error correction of RH based on computational fluid dynamics (CFD). Firstly, considering the solar radiation, the distribution of temperature field of MEMS humidity sensor is simulated from the ground to 32km altitude by using CFD soft under the boundary condition of fluid-solid coupled heat transfer. Secondly, the numerical analysis model of RH is put forward for solar radiation dry bias (SRDB) correction based on the working principle of the MEMS capacitive humidity sensor and the definition of RH. The results of numerical analysis show that the error of RH caused by solar radiation is nonlinearly increased with the altitude. Meanwhile the errors decrease with the reflectivity of sensor or of solder point increase. The simulation data also indicate that the SRDB can be reduced by improving the reflectivity of sensor or of solder point, adopting the substrate material with high thermal conductivity or choosing the suitable thickness of sensor. However, the SRDB should be corrected, for it still is more than 20% under the low atmospheric pressure. In this paper, the method based on fluid dynamics simulation provides a new way to correct the error of radiosonde MEMS humidity measurement caused by solar radiation heating.