Small Printed Circuit Board Research Articles

Diamagnetic measurements based on the compensation of TF current diffusion in J-TEXT.

Due to the existence both of toroidal ripples and toroidal field (TF) current diffusion, the toroidal flux changes with time when the TF current is at the flat-top. A diamagnetic measurement based on the compensation of TF current diffusion has been built in J-TEXT to solve this problem. The measurement system includes a double-loop installed in the vacuum vessel and an array of small printed circuit board (PCB) magnetic probes placed on the mid-plane of one TF coil. A model was proposed to analyze and compensate the effect of TF current diffusion. Experiment results show that the residual flux is about 1 × 10-4 Wb after the compensation and it can meet the need of diamagnetic measurement in J-TEXT.

Highly Efficient TiO2-Based Microreactor for Photocatalytic Applications

A photocatalytic, TiO2-based microreactor is designed and fabricated on a metal-titanium foil. The microchannel is mechanically engraved in the substrate foil, and a double-layered TiO2 anatase film is immobilized on its inner walls with a two-step synthesis, which included anodization and a hydrothermal treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm the presence of an approximately 10-μm-thick layer of titania nanotubes and anatase nanoparticles. The SEM and transmission electron microscopy (TEM) of the cross sections show a dense interface between the titanium substrate and the TiO2 nanotubes. An additional layer of TiO2-anatase nanoparticles on the top of the film provides a large, photocatalytic surface area. The metal-titanium substrate with a functionalized serpentine channel is sealed with UV-transparent Plexiglas, and four 0.8-mW UV LEDs combined with a power controller on a small printed-circuit board are fixed over the substrate. The photocatalytic activity and the kinetic properties for the degradation of caffeine are provided, and the longer-term stability of the TiO2 film is evaluated. The results show that after 6 months of use and 3600 working cycles the microreactor still exhibits 60% of its initial efficiency.

A wireless, compact, and scalable bioimpedance measurement system for energy-efficient multichannel body sensor solutions

In this paper, we present the design, realization and evaluation of a multichannel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz, and a low-cost commercially available radio frequency transceiver device, which provides reliable wireless communication. The resulting on-chip spectrometer provides high measuring EBI capabilities and constitutes the basic node to built EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multichannel EBI spectrometer where the number of nodes, i.e., number of channels, is completely scalable to satisfy specific requirements of body sensor networks. One of its main advantages is its versatility, since each EBI node is independently configurable and capable of working simultaneously. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery. A specifically tailored graphical user interface (GUI) for EBI-WSN has been also designed and implemented in order to configure the operation of EBI nodes and the network topology. EBI analysis parameters, e.g., single-frequency or spectroscopy, time interval, analysis by EBI events, frequency and amplitude ranges of the excitation current, etc., are defined by the GUI.

Smart wireless sensing and assessment for civil infrastructure

Recently, there has been increasing need for adopting smart sensing technologies to structural health monitoring (SHM) applications for civil infrastructure. In this paper, the state of the art in smart wireless sensing and assessment techniques for civil structures are reviewed focusing on full-scale applications. Three types of smart wireless sensing technologies are discussed: wireless acceleration sensor-based SHM, wireless impedance-based SHM and an optics-based non-contact actuation and sensing technique. At first, vibration-based SHM using a dense array of wireless acceleration sensors is implemented to a cable-stayed bridge. The modal identification of the bridge and cable tension estimation are carried out using the ambient acceleration data. Measured data during a typhoon is also discussed. Secondly, impedance-based SHM using piezoelectric active sensors is presented focusing on hardware and software issues. A wireless impedance sensor node is presented for local SHM and neural network-based smart assessment algorithm is proposed to detect multi-type damages. Finally, a wireless power and data transmission method using laser and optoelectronic technologies is presented for non-contact measurement of guided waves and impedance, and subsequent damage detection. This method is embodied in a small printed circuit board, and the performance is validated on a lab-scale steel truss member.

A PDMS-Based Integrated Stretchable Microelectrode Array (isMEA) for Neural and Muscular Surface Interfacing

Numerous applications in neuroscience research and neural prosthetics, such as electrocorticogram (ECoG) recording and retinal prosthesis, involve electrical interactions with soft excitable tissues using a surface recording and/or stimulation approach. These applications require an interface that is capable of setting up high-throughput communications between the electrical circuit and the excitable tissue and that can dynamically conform to the shape of the soft tissue. Being a compliant material with mechanical impedance close to that of soft tissues, polydimethylsiloxane (PDMS) offers excellent potential as a substrate material for such neural interfaces. This paper describes an integrated technology for fabrication of PDMS-based stretchable microelectrode arrays (MEAs). Specifically, as an integral part of the fabrication process, a stretchable MEA is directly fabricated with a rigid substrate, such as a thin printed circuit board (PCB), through an innovative bonding technology-via-bonding-for integrated packaging. This integrated strategy overcomes the conventional challenge of high-density packaging for this type of stretchable electronics. Combined with a high-density interconnect technology developed previously, this stretchable MEA technology facilitates a high-resolution, high-density integrated system solution for neural and muscular surface interfacing. In this paper, this PDMS-based integrated stretchable MEA (isMEA) technology is demonstrated by an example design that packages a stretchable MEA with a small PCB. The resulting isMEA is assessed for its biocompatibility, surface conformability, electrode impedance spectrum, and capability to record muscle fiber activity when applied epimysially.

On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Soil hydraulic properties in field scale porous media are distributed with large spatial heterogeneity. Thus, detailed understanding of micro-physical properties leading to macro-scale heterogeneity is important for generalizing purposes in modeling. Hysteretic water retention properties greatly affect solute transport under unsaturated condition. In this study, laboratory infiltration experiments were carried out to investigate the importance of hysteresis in numerical modeling of water flow under heterogeneous distribution of hydraulic conductivity. Soil water content was observed by time domain reflectometry using small printed circuit board probes (PCBP). The PCBP observations were compared to results from numerical simulations involving saturated-unsaturated seepage analysis and two-phase flow with/without hysteresis effects. Observations were compared to both uniform and heterogeneous parameter modeling. Differences between unsaturated-saturated and two-phase flow were quite small in the numerical results for soil water content. The uniform parameter model, however, could not properly reproduce experimental water content change. The numerical results of water content change including hysteresis matched better observations for the unsaturated-saturated and two-phase flow cases. Results displayed that it is important to take heterogeneity and hysteresis into consideration in the numerical modeling in both two-phase and saturated-unsaturated flow analysis. (Less)

Life-Cycle Monitoring and Voltage-Managing Unit for DC-Link Electrolytic Capacitors in PWM Converters

A novel life-cycle monitoring and voltage-managing device for dc-link electrolytic capacitors in pulsewidth modulation converters is presented. The system performs online identification of the capacitor's equivalent series resistance (ESR) in order to detect the life-cycle status and permit preventive maintenance. The ESR detection is based on the capacitor's ac losses calculated from voltage/current measurements using a simple low-cost microcontroller. The unit is designed as small printed circuit board located directly at the capacitor's screw terminals in order to simplify the required temperature sensing and to minimize wiring effort. The minimized energy consumption allows a power supply taken out of the capacitor to be tested. Besides life-cycle monitoring, the unit further facilitates energy-efficient voltage balancing for capacitors in series arrangements avoiding any power resistors typically used in balancing circuits. Instead, the unit controls the capacitor voltage by influencing its power consumption. Each individual monitoring unit (one per each power capacitor of the converter) transfers the ESR results to the converter's main controller and receives control commands via a common optoisolated fieldbus. Alternatively, this data transfer is performed using wireless near-field communication leading to a completely autonomous monitoring unit without any wiring for power supply and data transmission.

Passive Immersion Cooling of 3-D Stacked Dies

Three-dimensional die stacking increases integrated circuit (IC) density, providing increased capabilities and improved electrical performance on a smaller printed circuit board (PCB) footprint area. However, these advantages come at the expense of higher volumetric heat generation rates and decreased thermal and mechanical access to the die areas. Passive immersion cooling, allowing for buoyancy-driven fluid flow between stacked dies, can provide high heat transfer coefficients directly on the die surfaces, can easily accommodate a wide variety of interconnect schemes, and is scalable to any number of dies. A methodology for the optimization of immersion cooled 3-D stacked dies is presented, including the effects of confinement on natural convection and channel boiling. Optimum die spacings for both single and two phase cooling with saturated FC-72 are found to be on the order of half a millimeter for typical microelectronics geometries and to yield heat densities of 10-50 W/cm3 in natural convection and 100-500 W/cm3 in channel boiling.

Compact programmable network display system for portable projectors

This paper describes a compact display system with a network interface designed to receive video signals from an external server device such as a PC. This system has been built on a small printed circuit board (PCB) with an embedded DSP&CPU chip, and has been integrated into our prototype portable projector. With this PCB, the projector is capable of displaying multiple PC desktop screens from remote PCs connected through a network on a single projector screen. In addition, using the DSP's ability to decode compressed audio and video signals, the projector can be used to display network video streaming. In order to minimize its size the network interface is made detachable by using a network adaptor on a USB port. This architecture makes it highly configurable and easy to change its functions according to customers' needs. Following the description of its hardware and software architecture, we set forth the method introduced to debug the system software with the final prototype board using the wireless network connection established through the USB wireless LAN network adaptor.

The Making of the First Microprocessor

Although I didn't know it at the time, my early work experience turned out to be absolutely invaluable, setting the stage for my future career. Born, raised, and educated in northern Italy, I graduated in radio technology from the A. Rossi Technical Institute in Vicenza in 1960. My first job was assistant engineer at the Olivetti Electronic R&D Laboratory near Milan, where Olivetti was developing its early electronic computers. By a series of fortunate coincidences, in 1961 I ended up codesigning and building a small experimental electronic computer with 4K words of magnetic core memory. I was only 19 years old, and I had four technicians working for me, helping with the construction of that computer. The computer used approximately 1,000 logic gates, made with germanium transistors (fabricated in Italy by SGS-Fairchild), housed in a couple of hundred small printed circuit boards. Silicon transistors would have been faster, but they were too expensive, and integrated circuits (ICs) had just been invented and were not yet commercially available.

MEMS-Switched, Frequency-Tunable Hybrid Slot/PIFA Antenna

A microelectromechanical systems (MEMS)-switched, frequency-tunable hybrid slot/planar inverted-F antenna (PIFA) is demonstrated. The antenna occupies a small printed circuit board (PCB) space and is capable of operating between 2 and 5 GHz with three digital tuning steps. The measured mismatch-corrected efficiency is better than 60% between 2 and 5 GHz. The specific absorption rate (SAR) for an input power of 100 mW is less than 0.45 W/kg averaged over 1 g of tissue and 0.31 over 10 g of tissue assuming a system duty cycle of 0.5.

LABORATORY EXPERIMENT ON REACTIVE TRANSPORT IN PHYSICALLY AND CHEMICALLY HETEROGENEOUS FIELD

In general, hydro-geochemical characteristics of field soil porous media are distributed with large heterogeneity. This heterogeneity affects not only physical parameters but also chemical parameters. Evaluation of chemical and physical heterogeneity effects on transport of contaminant species is important to understand basic transport characteristics of field soils. In this study, laboratory experiment of solute transport in heterogeneous field with cation exchange reaction was carried out. Electric conductivities (EC) were measured by time domain reflectometry (TDR) using small printed circuit board probes (PCBP) . Transient concentrations of cations and anions of eluted water were analyzed by ion chromatography. Breakthrough curves (BTC) of injected K+ and Cl- showed split peeks that may be the effect of heterogeneity of the flow field. According to cations BTC, Ca and Mg were exchanged with K and then flushed out. Both of chemical and physical heterogeneity affects on solute transport clearly.

Electronic radon monitoring with the CMOS System-on-Chip AlphaRad

The development of the integrated circuit AlphaRad as a new System-on-Chip for detection of α-particles has already been reported. This paper deals with electronic monitoring of atmospheric radon, which is one of the promising applications of the chip. The future electronic radon monitor (ERM) is designed to be compact, inexpensive, operating at low voltage and fully stand-alone. We present here the complete electronic board of the future ERM: it is made of three independent AlphaRad chips running in parallel, mounted on a small printed-circuit board which includes a numeric block for data treatment based on a Xilinx programmable gate array. The maximal counting rate of the AlphaRad chip has been pushed to at least 3×10 6 α-particles cm −2. The complete system for detection of the solid aerosols will be published separately, and this paper will focus on the electronic board alone. Already 20 times faster than our first measurement with a CMOS pixel sensor, the system was tested at low and high activities, showing an excellent linearity for 222Rn levels up to 80 kBq m −3.

WATER INFILTRATION INVESTIGATIONS IN UNSATURATED-HETEROGENEOUS FIELD BY TDR METHOD USING PRINTED CIRCUIT BOARD PROBE AND BY IMAGE ANALYSIS

Hydrogeological parameters of field soil porous media are distributed with large heterogeneity. Evaluation of physical heterogeneity effects on soil water flow is important to understand basic flow characteristics of field soil. In this study, two types of water infiltration experiments were applied to examine water flow under the heterogeneous distribution of hydraulic conductivities. Time series of soil water change was measured by time domain reflectometry (TDR). In the TDR system, the small printed circuit board probes (PCBP) were used as wage guide. To evaluate soil water distribution change in the experimental sand box, the simple image analysis of digital photo of the experiments was proposed and tested. According to the TDR measurement, probes show clear response for ponding timing in the stepwise ponding experiment. Once soils were filled with water, they kept water in the continuous infiltration experiment using rain generator. The order of breakthrough match sequential photo of the continuous infiltration experiment. Preferential flow was clearly observed in the both experiments.

Compact Planar Antennas for Short-Range Wireless Automotive Communication

This paper describes several small printed circuit board planar antennas that can be integrated with amplifiers for short-range vehicle wireless communication. The antennas are designed for the 315-MHz frequency band, which is commonly used for control and security devices in the USA and Canada. Each antenna has dimensions of 50 /spl times/ 70 mm (much less than the free-space wavelength /spl lambda/=0.95 m) and is implemented on FR-4 dielectric substrate. These investigated antennas were compared with respect to input impedance, radiation resistance, radiation efficiency, directivity, directionality, bandwidth, matching system complexity, and gain. This paper also includes experimental verification of the final antenna design in the vehicle. It is shown that the antenna diversity method can increase communication range for remote keyless entry systems.

Statistical process control: examination of use in a small printed circuit board manufacturer

The paper reports a study into the use of statistical process control (SPC) in a company employing some 100 people, in the production of complex and high technology printed circuit boards for aerospace and defence applications. The findings indicate considerable potential for the use of SPC. The continuing development of SPC should facilitate an increase by operating staff in their processes and improve awareness of process variation, and should also lead to an improvement of process conditions. It is pointed out that a variety of attitudes among operating staff were displayed to the perceived usefulness of SPC. In particular, there was confusion between specification limits and control limits, based on performance of the process, and concerns about the implications of narrow control limits.

Extensions of the closed form method for substrate thermal analyzers to include thermal resistances from source-to-substrate and source-to-ambient

The Fourier series/integral closed-form method for substrate thermal analyzers has been limited by the specification of heat sources on the substrate surface. A method of complementing the basic substrate boundary value problem with lumped thermal resistances is described. In this manner, the thermal interface resistance between a chip package and board, as well as between the same package and a local ambient can be accommodated. The technique consists of combining the methods of Fourier series solution and lumped parameter thermal resistances. The theory is verified by comparing results with both thermal network and finite element model calculations for a sample problem consisting of four active devices attached to a substrate. The ramifications of a uniform heat flux at the board surface are examined by evaluating an approximate representation of a surface mount chip package. Results are compared with experimental test data for a small printed circuit board with 56 dual in-line resistor packs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of a fast gated charge integrating front end for use in high density CAMAC and fastbus modules

This paper describes the design principles of two versions of a gated charge integrating front end for use with high energy physics particle detectors. The current integration, gate and clear problems are discussed. A high slew rate design and its implementation on a very small printed circuit board is presented. The design of a 32 channel, 12 bit CAMAC charge integrating ADC is outlined.