Study of an Online Monitoring Adaptive System for an Injection Molding Process Based on a Nozzle Pressure Curve.

Injection molding is a popular process for the mass production of polymer products, but due to the characteristics of the injection process, there are many factors that will affect the product quality during the long fabrication processes. In this study, an adaptive adjustment system was developed by C++ programming to adjust the V/P switchover point and injection speed during the injection molding process in order to minimize the variation of the product weight. Based on a series of preliminary experiments, it was found that the viscosity index and peak pressure had a strong correlation with the weight of the injection-molded parts. Therefore, the viscosity index and peak pressure are used to guide the adjustment in the presented control system, and only one nozzle pressure sensor is used in the system. The results of the preliminary experiments indicate that the reduction of the packing time and setting enough clamping force can decrease the variation of the injected weight without turning on the adaptive control system; meanwhile, the master pressure curve obtained from the preliminary experiment was used as the control target of the system. With this system, the variation of the product weight and coefficient of variation (CV) of the product weight can be decreased to 0.21 and 0.05%, respectively.

Study of a Compression-Molding Process for Ultraviolet Light-Emitting Diode Exposure Systems via Finite-Element Analysis.

Although wafer-level camera lenses are a very promising technology, problems such as warpage with time and non-uniform thickness of products still exist. In this study, finite element simulation was performed to simulate the compression molding process for acquiring the pressure distribution on the product on completion of the process and predicting the deformation with respect to the pressure distribution. Results show that the single-gate compression molding process significantly increases the pressure at the center of the product, whereas the multi-gate compressing molding process can effectively distribute the pressure. This study evaluated the non-uniform thickness of product and changes in the process parameters through computer simulations, which could help to improve the compression molding process.

Finite Element Analysis of Film Stack Architecture for Complementary Metal-Oxide-Semiconductor Image Sensors.

Image sensors are the core components of computer, communication, and consumer electronic products. Complementary metal oxide semiconductor (CMOS) image sensors have become the mainstay of image-sensing developments, but are prone to leakage current. In this study, we simulate the CMOS image sensor (CIS) film stacking process by finite element analysis. To elucidate the relationship between the leakage current and stack architecture, we compare the simulated and measured leakage currents in the elements. Based on the analysis results, we further improve the performance by optimizing the architecture of the film stacks or changing the thin-film material. The material parameters are then corrected to improve the accuracy of the simulation results. The simulated and experimental results confirm a positive correlation between measured leakage current and stress. This trend is attributed to the structural defects induced by high stress, which generate leakage. Using this relationship, we can change the structure of the thin-film stack to reduce the leakage current and thereby improve the component life and reliability of the CIS components.

Consideration of different heating lengths of needles with induction heating and resistance system: A novel design of needle module for thermal ablation.

Thermal ablation using alternating electromagnetic fields is a promising method to treat tissues including tumors. With this approach, an electromagnetic field is generated around an induction coil, which is supplied with high frequency current from a power source. Any electrically conducting object, which is placed in the electromagnetic field, is then heated due to eddy currents. Basic principles underlying this novel thermotherapy needle system are internal induction and resistance heating. This presents a new design of a standard gauge 18 percutaneous trans-hepatic cholangiography needle module combined with a compact power source. Three needle modules containing coils of different lengths were used to locally heat up different volumes of tissues in in vitro experiments on pig livers. Temperature on the inside surface of the needle was controlled and monitored through a K-type thermocouple. By using this needle module system, no two-section or ferromagnetic nanoparticle-coated needles were required; the system worked well with the SUS-304 stainless-steel needle. Successful results were demonstrated in the in vitro experiments on pig livers with different heating lengths of 10, 20, and 30 mm needles. With low power sources, needles could be heated up to a high temperature. The novel design of the needle module incorporated with a high frequency power source was thus shown to be a promising technology for tissue ablation. Bioelectromagnetics.38:220-226, 2017. © 2016 Wiley Periodicals, Inc.

Integrated microfluidic system for electrochemical sensing of urinary proteins.

This study reports a new microfluidic system integrated with a microfluidic control module and a micro electrochemical module for detection of urinary proteins. The integrated microsystem can automatically detect proteins in urine with a high sensitivity. The microfluidic control module consists of a new two-way, spiral-shape micropump which can transport the urine samples to the sensing regions. The net ionic charges of the protein samples can be detected while the samples flow through the sensing region of the micro electrochemical module. Two major urinary proteins including lysozyme and albumin are detected in a multiple-channel layout with little human intervention and are analyzed in a short period of time, while only consuming a 100-mul urine sample. The developed microfluidic system could lead to a convenient, yet crucial, platform for chemical and biological detection and diagnosis.

Microfluidic pH-sensing chips integrated with pneumatic fluid-control devices.

This paper presents a microfluidic chip capable of performing precise continuous pH measurements in an automatic mode. The chip is fabricated using micro-electro-mechanical-systems (MEMS)-based techniques and incorporates polydimethylsiloxane (PDMS) microstructures, pH-sensing electrodes and pneumatic fluid-control devices. Through its enhanced microchannel design and use of pneumatic fluid-control devices, the microfluidic chip reduces the dead volume of the sample and increases the pumping rate. The maximum pumping rate of the developed micro-pump is 28 microL/min at an air pressure of 10 psi and a driving frequency of 10 Hz. The total sample volume consumed in each sensing operation is just 0.515 microL. As a result, the developed chip reduces the sample volume compared to conventional large-scale pH-sensing systems. The microfluidic chip employs the electrochemical sensing method to conduct precise pH level measurements. The sensing electrodes are fabricated by sputtering a layer of SiO(2)-LiO(2)-BaO-TiO(2)-La(2)O(3) (SLBTLO) onto platinum (Pt) electrodes and the pH value of the sample is evaluated by measuring the potential difference between the sensing electrodes and a reference electrode. Additionally, the integration of the microfluidic chip with a pneumatic fluid-control device facilitates automatic sample injection and a continuous sensing operation. The developed system provides a valuable tool with which to examine pH values in a wide range of biomedical and industrial applications.