Papers by Author: Po Kuang Chang

Abstract: This research applied a stylus probe without balance and lever arm as in the previous design of a contact-force-controlled Scanning Probe Microscope (SPM) system. The controller integrated both Ziegler-Nichols-based and intelligent fuzzy methods; thus the systems relative stability can be reserved under the nominal conditions. In addition, one can see that both hysteresis and parameter variation effects of the force actuator can be reduced. Comparing the results with the traditional Ziegler-Nichols-based controller by simulation, one can see that the proposed systems are much more robust.

Abstract: Conventional bio-probes are produced on a silicon substrate, they are not only fragile but unable to dispose according to the profile of human body in a large area manner, and thus the contact resistance between probe and skin may be increased. Besides, the signal processing devices are required to improve both S/N ratio and impedance matching problems. This paper proposes a novel remote human health monitor and an active RFID tag with replaceable non-frangible probes and thin-film-transistor (TFT) amplifiers. The probes are made of bio-degradable polymer (photo resist) and covered with bio-compatible TiN. In addition, we use two pieces of double sides conducting tapes to connect both TFT amplifiers and probe modules. Thus the probe module can be replaced easily by peeling the used probe module away from the double sides conducting tapes to supply a new one. Since the tag is a flexible plastic substrate, e, g. PT, PET and PI, so the probes are easier to deploy and conform to the human body profile. In addition, the signal can be amplified by the TFT amplifier nearby to improve both S/N ratio and impedance matching. Thus the human health conditions can be remotely monitored by measuring various acupuncture impedances via the active RFID tag. The active RFID monitoring range is 15m by using 2.45 GHz ISM band, the probe resistance and parasitic capacitance are as 2735 Ω and 60.7 pf, respectively. Since the typical human acupuncture point resistance is about 40-120KΩ, thus the proposed device and system can be applied.

Abstract: This research proposes a novel low temperature manufacturing method to make a wireless accelerometer on a flexible substrate. The substrate deposition temperature is 100°C without causing any strain and stress problem. Since the thermal conductivity of the traditional Si is 1.48 W/ (cm-K), which is 25 times of the flexible substrate, i.e. 0.06-0.0017 W/ (cm-K), thus the power leakage through the substrate can be saved by the new design. The key technology is to integrate a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for fabrication and usage. In this paper the heaters and the thermal piles are directly adhering on the substrate surface without the traditional floating structure. Thus the structure is much simpler and cheaper for manufacturing, and much more reliable in large acceleration impact condition without broken. Furthermore, the molecular weight of xenon gas (131.29 g/mol) is much larger than carbon dioxide (44.01 g/mol), thus the performance of the accelerometer will be increased. In addition, the shape of the chamber is changed as a semi-cylindrical one instead of the conventional rectangular type. The average sensitivity is increased by 15%. In addition, if one applies only xenon gas but keeping the rectangular chamber, then the response speed can be increased by 23%. Moreover, if one applies both Xe and the semi-cylindrical chamber, then the response speed can be increased by 43%.

Abstract: This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture and package it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for fabrication and usage. In this paper the heaters as well as the thermal sensors are directly adhering on the surface of the flexible substrate without the traditional floating structure. Thus the structure is much simpler and cheaper for manufacturing, and much more reliable in large acceleration impact condition without broken. Furthermore, the molecular weight of xenon gas is much larger than carbon dioxide, thus the performance of the accelerometer will be increased. In addition, the shape of the chamber is changed as a semi-cylindrical one instead of the conventional rectangular type. Comparisons of sensitivity and response time are also made; one can see the performances of the proposed new design with either semi-cylindrical chamber or filled with xenon gas are better.

Abstract: This research is to extend Ziegler-Nichols based PID controller design method to the intelligent fuzzy PID controller design of a Scanning Probe Microscope (SPM) system, thus the relative stability can be reserved. In addition, one can see the hysteresis and parameters variation effects of the force actuator can be reduced. This improvement had been verified by practical implementation. Comparing the results with the design with the Ziegler-Nichols based PID controller, one can see that the proposed system is more robust.

Abstract: This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for usage. In this paper we use xenon inert gas in the chamber with heavier molecular weight to increase the acceleration sensitivity instead of traditional air or carbon dioxide. On the other hand, the specific heat of xenon gas is also lower so that the bandwidth of the proposed accelerometer is larger and the power consumption is lower. In addition, the inner shape of the chamber is changed as hemisphere instead of rectangular type, comparisons are also made. We have seen that the sensitivity of the proposed design is better.

Abstract: This paper integrated multi-domain knowledge of electronics, optics, control as well as precision measurement, and proposing a high resolution subdividing electronics module to the sinusoidal encoder output of a positioning motor, such that the module can not only be used as a counter for linear and/or angular measurements, but also subdivide the periods of the sinusoidal encoder signals up to 1600 times. From the results of experiment test it can be seen that the whole module is suitable for those applications requiring high-resolution encoder, nanometer measurement as well as fast data acquisition with phase tolerance of ± 45°.

Abstract: The key point of this research is to use Linear Velocity Transducer (LVT) to detect the vertical velocity of the stylus probe for the inner-loop damping and transient control of a force actuator. This improvement has been verified by MATLAB simulation and practical implementation of a surface profiler to reduce the hysteresis effect of the force actuator.