Key Engineering Materials Vols. 645-646

Abstract: A second order differential filter with Q-enhancement and tunable active inductor is presented. The design technique for a tunable Q-enhancement SiGe HBT active inductor operating in the wide RF-band for the filter is described. Multi-regulated Cascode circuit is employed to enhance the quality factor Q by increasing the output impedance. Tunable active resistor is introduced to boost the tuning ability of the active inductor. Employing the proposed active inductor, the center frequency of the filter is tuned in the frequency of 1.05~2.45GHz by adjusting the bias current, Q reducing with different bias current can be compensated via tuning the feedback effective resistance of the active inductor, and Q has almost constant value of 209~225 at the frequency of 2.15GHz.

Abstract: This paper studies a new trajectory guidance logic system for Bank-To-Turn fixed-wing (BTT) micro air vehicle (MAV) based on MEMS sensor / GPS , and introduce the method of estimating the navigation information from MEMS sensors and GPS. a nonlinear guided logic based on literature is utilized to get the desired roll angle , and a total energy controller is utilized in the longitudinal loop. Based on the kinematic model of the coordinated turning of MAV, the system can ensure that the aircraft stably track a flight plan segment. Flight tests on MAV prove the feasibility of the trajectory guidance logic system.

Abstract: Aiming to be applied in silicon gyroscope, a three-order single loop feedforward modulator with three-bit quantizer and local feedback is designed in this paper. Signal band is 200 KHz, sampling rate is 25.6 MHz, OSR is 64. Ideal modulator is then designed and simulated in MATLAB, getting SNR 125dB. Non-ideal factors are also added to ideal model, DWA technology is adopted to restrain the nonlinearity of multi-bit quantizer, getting SNR 104dB. Finally, transistor-level full-difference modulator is designed and simulated in Cadence, fetting SNR 101.3dB.

Abstract: This paper presents a novel capacitive sensor for real-time monitoring of temperature in the silicone oil fan clutch. The structure of the temperature sensor is designed and fabricated by the Silicon-On-Glass (SOG) process based on the bonding technology. The silicone oil is designed as the temperature sensing materials in the capacitive sensor. The capacitance of the embedded sensor is changing with respect to temperature of the silicone oil fan clutch. Experimental results show that the sensor provides a sensitivity of 27.3fF/°C in the -30 to 40°C range, 58.2fF/°C in the 50 to 110°C rang. It is also demonstrated that the temperature sensitive capacitor can be integrated with a copper inductance antenna and tests as a passive wireless temperature sensor. The resonant frequency of the inductor-capacitor (LC) resonator changes with respect to the changing capacitance. Then temperature changes can be remotely determined towards a frequency spectrum study. Experimental results show that the LC type passive wireless sensor provides a sensitivity of 6.35kHz/°C in the -30 to 110°C range.

Abstract: Active disturbance rejection control (ADRC) as an alternative to classical PID control to solving control problems, has gained significant traction these years. With its simple tuning method, robustness against process parameter variations and ability of disturbance rejection, we tried it in our homemade fast atomic force microscope (AFM). Experiments are carried out in contact mode on standard optical grating sample with 50Hz line rate. The results show that ADRC can reject external disturbances well, and can reduce system vibrations obviously.

Abstract: Properties of materials and their variations in depth direction in the same location could be measured directly by progressive multi-cycle (PMC) nanoindentation method. But influences of strain-hardening on measured results in this process haven’t been researched thoroughly. Measurements on an austenitic steel sample and a fused silica sample were conducted by PMC nanoindentation and standard nanoindentation methods, and differences of the results by two methods of the two materials were analyzed. It was found that hardness of austenitic steel measured by PMC method decreased monotonously with increased depth, while hardness measured by standard method decreased to stable value with increased depth. And properties of fused silica measured by both methods accorded much well. Based on analysis of plastic strain during indentation process, it was deduced that austenitic steel with high plasticity could introduce second convergence of plastic strain and stress in PMC indentation process, which made measured hardness decrease monotonously with increased depth.

Abstract: As concentration of components in environmental gas is very low, and the available analytical instruments are not sufficiently sensitive, so that micro pre-concentrators developed for effectively concentrating components are very important and necessary. Therefore, in this work a micro pre-concentrator was fabricated for concentrating trace gas. The micro pre-concentrator with 4 parallel channels filled with Single-Walled Carbon Nanotubes (SWCNTs) as adsorbent materials was developed for concentrating volatile organic compounds (VOCs). This choice was done on the basis of the consideration: 4 parallel channels ensure that the pre-concentrator can be filled with a sufficient amount of adsorbent materials. Moreover, SWCNTs was acted as adsorbent material owing to their chemical and thermal stability, a high surface-to-volume ratio, and a large affinity to the non-polar compounds. The experimental results show that the micro pre-concentrator effectively concentrated benzene with a concentration factor of 15 and the chromatography peak broadening was also greatly compressed.

Abstract: Hydraulic system is widely used in the ship, when the diameter of tiny particles in hydraulic oil exceeds 20μm it indicates that the abnormal wear occurred and the malfunction may cause. This paper uses the light blockage method, the microfluidic detection chip for hydraulic oil detection has been designed and fabricated, a simple and effective optical detection system is developed with the signal amplification and data collection to achieve the detection of tiny particles, and finally through the JAVA programming to count the number of particles in which the diameter is more than 20μm. The results of rapid detections on iron particles with diameter between 25μm and 38μm show the good performance of the detection system and prove that the method is feasible.

Abstract: Microgram weights have a wide range of applications in the mechanical testing of bio-material sensors and nanotechnology market which typically involves the manufacture of objects with dimensions of less than 100 nanometers. Now it is available with a calibration certificate in National Institute of Metrology (China) that customers can be assured of full traceability to the national primary standard of mass, NO.60, which make allow customers with specialized nanotechnology applications to use the weight values range from 0.05 mg to 0.5 mg with standard uncertainty of just 0.3 μg to 0.08μg.In the paper, an effective method was developed to calibrate weights, along with new methods of calculating uncertainties that would satisfy OIML R111 requirements. This new calibration method involved comparing the weights with the 1 mg standard mass standards using a combination of subdivision and substitution weighing scheme.

Abstract: Vacuum gauge based on micro hotplate (MHP) is a kind of promising MEMS vacuum gauge due to its advantages including high sensitivity, wide measurement range, fast response speed and comparably easy fabrication, etc. In this paper, through analyzing various of heat dissipation approaches including solid heat conduction, gas heat conduction, heat radiation, and convection, the sensor output expression of MHP-based vacuum gauge is obtained when keeping electric current of heating resistor constant. With the structure size and material properties, the relationship curve between vacuum gauge output and gas pressure can be obtained. By wet etching silicon under the compound dielectric films with embedded metal film resistor, MHP suspended over silicon substrate is fabricated. Then the sensor chip is assembled and put into vacuum system, and test is conducted when keeping the heating resistor at constant heating current of 5mA. The measurement results show that the sensor measurement range is 5×10^-3Pa~10³Pa, which is basically consistent with the theoretical analyzing results.