scholarly journals Novel Portable Sensing System with Integrated Multifunctionality for Accurate Detection of Salivary Uric Acid

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 242
Author(s):  
Ziqi Liu ◽  
Yiyin Chen ◽  
Meng Zhang ◽  
Tiancheng Sun ◽  
Keer Li ◽  
...  
Keyword(s):  
Uric Acid ◽  
Printed Circuit Board ◽  
Simple Procedure ◽  
The Body ◽  
Circuit Board ◽  
Future Application ◽  
Sensing System ◽  
The Difference ◽  
Novel Strategy ◽  
The Cost

Uric acid, as the terminal product of purine metabolism in the body, is an important marker of many diseases. Uric acid is abundant in saliva, offering the possibility of its non-invasive detection. However, it is sensitive to interference in saliva by a variety of factors. A reliable method of processing saliva is centrifugation (CF), but the cost and size of equipment limit its use in everyday life. In this study, a novel portable salivary-sensing system (PSSS) with integrated suction filtration (SF) and temperature insulation was proposed to obtain more accurate salivary uric acid levels through a simple procedure. The PSSS includes a saliva container, a high-sensitive uric acid sensor (UAS), an accompanying printed circuit board (PCB), and a mobile application. The responses produced by the UAS presents excellent linearity (4.6 μA/mM with R2 = 0.9964), selectivity, reproducibility, and stability for the detection of low levels of uric acid. The difference in detection values between the UAS and the commercial sensor is only ~4%. The primary feature of the saliva container is the processing of saliva by SF instead of CF. Samples from CF and SF showed no significant differences regarding uric acid levels, and both exhibited approximately 50% deviation from the untreated samples, while the difference in uric acid levels between the samples after SF and after applying both treatments was ~10%. Besides, insulation of the saliva container can partially eliminate sources of error induced by the environment during uric acid level testing. The PSSS provides a novel strategy for the immediate detection of specific markers in saliva. We believe that the PSSS has promising potential for future application in the rapid saliva testing.

scholarly journals Wideband Rectangular Foldable and Non-foldable Antenna for Internet of Things Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-5 ◽  
Author(s):  
Steve W. Y. Mung ◽  
Cheuk Yin Cheung ◽  
Ka Ming Wu ◽  
Joseph S. M. Yuen
Keyword(s):  
Internet Of Things ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Design Parameters ◽  
Multiple Frequency ◽  
Wireless Applications ◽  
Printed Circuit ◽  
Iot Applications ◽  
Trade Offs ◽  
The Cost

This article presents a simple wideband rectangular antenna in foldable and non-foldable (printed circuit board (PCB)) structures for Internet of Things (IoT) applications. Both are simple structures with two similar rectangular metal planes which cover multiple frequency bands such as GPS, WCDMA/LTE, and 2.4 GHz industrial, scientific, and medical (ISM) bands. This wideband antenna is suitable to integrate into the short- and long-range wireless applications such as the short-range 2.4 GHz ISM band and standard cellular bands. This lowers the overall size of the product as well as the cost in the applications. In this article, the configuration and operation principle are presented as well as its trade-offs on the design parameters. Simulated and experimental results of foldable and non-foldable (PCB) structures show that the antenna is suited for IoT applications.

A MEMS Magnetometer Utilizing a NdFeB Magnet

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001671-001700
Author(s):  
John J. Tatarchuk ◽  
Colin B. Stevens ◽  
Robert N. Dean
Keyword(s):  
Magnetic Fields ◽  
Printed Circuit Board ◽  
Relaxation Oscillator ◽  
Circuit Board ◽  
Ndfeb Magnet ◽  
Assembly Method ◽  
Variable Capacitance ◽  
The Difference ◽  
Silicon Frame ◽  
Gap Width

A silicon MEMS magnetometer has been developed that utilizes a miniature NdFeB rare earth magnet attached to a silicon platform that is suspended by a dual torsional suspension system. An externally applied out-of-plane magnetic field will cause a magnetic torque to be produced between the external field and the NdFeB magnet, causing a deflection of the suspended silicon platform which can be sensed capacitively. The device measures 5.6 mm X 5.6 mm, with the silicon components being manufactured using bulk micromachining processes. The variable capacitive structure is realized by metalizing the bottom side of the suspended silicon platform to allow the silicon platform to serve as the top electrode. The bottom electrode is provided by a bare pad on a printed circuit board (PCB) to which the frame of the silicon device is attached. This results in a variable capacitance with a nominal value of approximately 3–6 pF, depending on the exact width of the gap. The variable capacitance is large enough to be converted into a variable frequency square wave using a CMOS relaxation oscillator circuit. To realize a practical device, multiple silicon components were manufactured. First, a silicon component had to be manufactured that included the anchor/frame, torsional springs, and suspended platform. To provide protection against destructive over-ranging of the mechanical components during very high accelerations or external magnetic fields, another silicon component was manufactured that provided mechanical stops at the limits of the useful displacement range. Two other components were also manufactured on the same wafer to provide for a cap over the device. Epoxy was used to bond the NdFeB magnet and the various silicon components together. The fabricated devices behaved similarly to their predicted theoretical performance, with a nominal oscillation frequency around 30 kHz, a sensitivity around 100 nT/Hz, and a noise floor around 50 nT. Several fabrication and assembly issues had to be solved in order to realize the device. The gap width of the capacitive structure is dependent on the thickness of the agent used to electrically connect the silicon anchor to a pad on a PCB. As it is desirable to minimize this gap width, some experimentation was required to find a suitable agent and assembly method. Additionally, the bonding agent used to attach the silicon anchor to the PCB must be applied at a temperature near the expected operating temperature of the device to prevent large stresses from being applied to the silicon frame due to the difference in the coefficients of thermal expansion between silicon and FR4. Also, during fabrication it was found that large flat areas, where a very uniform etch is critical, required wet KOH etching, while deep reactive ion etching could be used for areas where depth and a high aspect ratio were important. Significance This MEMS sensor represents a novel configuration for sensing magnetic fields. Without much optimization, the sensor already exceeds the sensitivity of many commercially available Hall-effect based MEMS magnetometers. As MEMS magnetometers are less developed than alternative magnetometer technologies, they may have more opportunities for improvement.

Fatigue Life Analysis of Solder Joints in Flip Chip Bonding

1999 ◽  
Vol 122 (3) ◽  
pp. 207-213 ◽  
Author(s):  
Yutaka Tsukada ◽  
Hideo Nishimura ◽  
Masao Sakane ◽  
Masateru Ohnami
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Electrical Potential ◽  
Potential Drop ◽  
Life Assessment ◽  
Circuit Board ◽  
Ratchet Effect ◽  
The Difference ◽  
Fatigue Life Analysis

This paper describes the life assessment of flip chip joints. Flip chip joints of 63Sn-37Pb and 5Sn-95Pb solders on a printed circuit board were stressed thermally for fatigue. Fatigue lives of the joints were determined by an electrical potential drop method and the effect of encapsulation on fatigue life was discussed. The encapsulation had a significant effect of prolonging the fatigue life of the joints. Thermo-mechanical finite element analyses proved that the encapsulation lowered the strain amplitude of the joints by distributing the strain over a whole package and bending effect. Cracking location was also discussed in relation with the strain concentration in the joints. Fatigue lives of the flip chip joints were compared with those of bulk round bar specimens and the difference in fatigue life between two types of specimens was discussed from the specimen dimensions and ratchet effect. [S1043-7398(00)00203-6]

scholarly journals Ka-Band Slot-Microstrip-Covered and Waveguide-Cavity-Backed Monopulse Antenna Array

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Li-Ming Si ◽  
Yong Liu ◽  
Yongjun Huang ◽  
Weiren Zhu
Keyword(s):  
Antenna Array ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Dielectric Substrate ◽  
Circuit Board ◽  
Slot Antenna ◽  
Ka Band ◽  
Operating Bandwidth ◽  
The Difference ◽  
Waveguide Slot Antenna

A slot-microstrip-covered and waveguide-cavity-backed monopulse antenna array is proposed for high-resolution tracking applications at Ka-band. The monopulse antenna array is designed with a microstrip with2×32slots, a waveguide cavity, and a waveguide monopulse comparator, to make the structure simple, reduce the feeding network loss, and increase the frequency bandwidth. The2×32slot-microstrip elements are formed by a metal clad dielectric substrate and slots etched in the metal using the standard printed circuit board (PCB) process with dimensions of 230 mm  ×  10 mm. The proposed monopulse antenna array not only maintains the advantages of the traditional waveguide slot antenna array, but also has the characteristics of wide bandwidth, high consistence, easy of fabrication, and low cost. From the measured results, it exhibits good monopulse characteristics, including the following: the maximum gains of sum pattern are greater than 24 dB, the 3 dB beamwidth of sum pattern is about 2.2 degrees, the sidelobe levels of the sum pattern are less than −18 dB, and the null depths of the difference pattern are less than −25 dB within the operating bandwidth between 33.65 GHz and 34.35 GHz for VSWR ≤ 2.

scholarly journals Elevated Standoff Heights of Solder Joint Interconnections Can Result in Appreciable Stress and Warpage Relief

2019 ◽  
Vol 16 (1) ◽  
pp. 13-20
Author(s):  
Ephraim Suhir ◽  
Sung Yi ◽  
Jennie S. Hwang ◽  
Reza Ghaffarian
Keyword(s):  
Solder Joint ◽  
Integrated Circuit ◽  
Printed Circuit Board ◽  
Solder Joints ◽  
Calculated Data ◽  
Circuit Board ◽  
Stress Model ◽  
Solder Material ◽  
The Difference ◽  
Ic Package

Abstract The “head-in-pillow” (HnP) defects in lead-free solder joint interconnections of Integrated Circuit (IC) packages with conventional (small) standoff heights of the solder joints, and particularly in packages with fine pitches, are attributed by many electronic material scientists to the three major causes: attributes of the manufacturing process, solder material properties, and design-related issues. The latter are thought to be caused primarily by elevated stresses in the solder material, as well as by the excessive warpage of the Printed Circuit Board (PCB)-package assembly and particularly by the differences in the thermally induced curvatures of the PCB and the package. In this analysis, the stress and warpage issue is addressed using an analytical predictive stress model. The model is a modification and an extension of the model developed back in 1980s by the first author. It is assumed that it is the difference in the postfabrication deflections of the PCB-package assembly that is the root cause of the solder material failures and particularly and perhaps the HnP defects. The calculated data based on the developed stress model suggest that the replacement of the conventional ball grid array (BGA) designs with designs with elevated standoff heights of the solder joints could result in significant stress and warpage relief and, hopefully, in a lower propensity of the IC package to HnP defects as well. The general concepts are illustrated by a numerical example, in which the responses to the change in temperature of a conventional design, referred to as BGA, and a design with solder joints with elevated standoff heights, referred to as column grid array (CGA), are compared. The computed data indicated that the effective stress in the solder material was relieved by about 40% and the difference between the maximum deflections of the PCB and the package was reduced by about 60%, when the BGA design was replaced by a CGA system. Although no definite proof that the use of solder joints with elevated standoff heights will lessen the package propensity to the HnP defects is provided, the authors nonetheless think that there is a reason to believe that the application of solder joints with elevated standoff heights could result in a substantial improvement in the general IC package performance, including, perhaps, its propensity to HnP defects.

scholarly journals Modelling of temperature distribution along PCB thickness in different substrates during reflow

Circuit World ◽  
2019 ◽  
Vol 46 (2) ◽  
pp. 85-92
Author(s):  
Daniel Straubinger ◽  
István Bozsóki ◽  
David Bušek ◽  
Balázs Illés ◽  
Attila Géczy
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
Vapour Phase ◽  
Circuit Board ◽  
Transfer Coefficients ◽  
Content Type ◽  
Printed Circuit ◽  
Heat Transfer Coefficients ◽  
Significant Temperature ◽  
The Difference

Purpose In this paper, analytical modelling of heat distribution along the thickness of different printed circuit board (PCB) substrates is presented according to the 1 D heat transient conduction problem. This paper aims to reveal differences between the substrates and the geometry configurations and elaborate on further application of explicit modelling. Design/methodology/approach Different substrates were considered: classic FR4 and polyimide, ceramics (BeO, Al2O3) and novel biodegradables (polylactic-acid [PLA] and cellulose acetate [CA]). The board thicknesses were given in 0.25 mm steps. Results are calculated for heat transfer coefficients of convection and vapour phase (condensation) soldering. Even heat transfer is assumed on both PCB sides. Findings It was found that temperature distributions along PCB thicknesses are mostly negligible from solder joint formation aspects, and most of the materials can be used in explicit reflow profile modelling. However PLA shows significant temperature differences, pointing to possible modelling imprecisions. It was also shown, that while the difference between midplane and surface temperatures mainly depend on thermal diffusivity, the time to reach solder alloy melting point on the surface depends on volumetric heat capacity. Originality/value Results validate the applicability of explicit heat transfer modelling of PCBs during reflow for different heat transfer methods. The results can be incorporated into more complex simulations and profile predicting algorithms for industrial ovens controlled in the wake of Industry 4.0 directives for better temperature control and ultimately higher soldering quality.

Thermal Analysis of Natural Convection Cooled Switch Mode Power Supplies

2003 ◽  
Author(s):  
Katsuhiro Koizumi ◽  
Akito Joboji ◽  
Kuniaki Nagahara ◽  
Masaru Ishizuka
Keyword(s):  
Natural Convection ◽  
Printed Circuit Board ◽  
Semiconductor Devices ◽  
Flow Simulation ◽  
Circuit Board ◽  
Switch Mode Power Supply ◽  
Power Semiconductor ◽  
Power Semiconductor Devices ◽  
Switch Mode ◽  
The Difference

This paper describes an application example of thermal flow simulation to the design of a switch mode power supply (SMPS) that is natural convection air-cooled. In this analysis, the modeling of printed circuit board (PCB) and power semiconductor devices was examined using the design of experiments method. The PCB was treated as a simple plate, and average thermal conductivity was not considered. The power semiconductor devices were modeled as a simple hexahedral resistive network block. As the heat generation sources, a field effect transistor (FET) and a diode were considered in the simulation, and the calculation method of power loss is described. The difference between measured and calculated values for power semiconductor devices was found to be within approximately 10 K.

The Use of Polymer Thick Film for Making Printed Circuit Boards

1982 ◽  
Vol 1 (1) ◽  
pp. 22-23 ◽  
Author(s):  
F.W. Martin
Keyword(s):  
Thick Film ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Electronics Industry ◽  
Circuit Board ◽  
Technical Knowledge ◽  
Circuit Boards ◽  
Printed Circuit ◽  
The Cost

The electronics industry is facing a situation in which the cost of electronic functions is dropping continuously while the cost of interconnecting the functions by traditional means, especially through the use of printed circuit boards, continues to rise. Polymer thick film is one proven approach to reversing the trend of rising interconnection costs. It is relatively easy for the typical printed circuit board manufacturer to convert to or adapt polymer thick film because he has most of the necessary equipment, technical knowledge and personnel.

Reducing Material Waste Using Six Sigma in Printed Circuit Board Assembly

2007 ◽  
Author(s):  
Naji E. Gebara ◽  
Badih Jawad
Keyword(s):  
Six Sigma ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Printed Circuit Board Assembly ◽  
Printed Circuit ◽  
Circuit Board Assembly ◽  
Project Controlling ◽  
Key Steps ◽  
The Cost ◽  
And Control

Material waste in the Printed Circuit Board Assembly consist of parts and components that are purchased above and beyond what is required to complete a project. Controlling such material waste identified in this paper as Quantity Variance is in a direct relationship to minimizing the cost of variance that increases the profitability of each job in a low volume high mix production. This Quantity Variance occurs as defects at key steps of the manufacturing process. Six sigma is used to define, measure, analyze and control occurrences resulting in the need to purchase additional components for the completion of the order.

scholarly journals Readout Distance Enhancement of the Passive Wireless Multi-Parameter Sensing System Using a Repeater Coil

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Lifeng Wang ◽  
Lei Dong ◽  
Qing-an Huang
Keyword(s):  
Power Supply ◽  
Printed Circuit Board ◽  
Supply Voltage ◽  
Copper Wire ◽  
Experimental Results ◽  
Circuit Board ◽  
Power Supply Voltage ◽  
Detection Distance ◽  
Sensing System ◽  
Backscatter Modulation

A repeater coil is used to extend the detection distance of a passive wireless multi-parameter sensing system. The passive wireless sensing system has the ability of simultaneously monitoring three parameters by using backscatter modulation together with channel multiplexing. Two different repeater coils are designed and fabricated for readout distance enhancement of the sensing system: one is a PCB (printed circuit board) repeater coil, and the other is a copper wire repeater coil. Under the conditions of fixed voltage and adjustable voltage, the maximum readout distance of the sensing system with and without a repeater coil is measured. Experimental results show that larger power supply voltage can help further increase the readout distance. The maximum readout distance of the sensing system with a PCB repeater coil has been extended 2.3 times, and the one with a copper wire repeater coil has been extended 3 times. Theoretical analysis and experimental results both indicate that the high Q factor repeater coil can extend the readout distance more. With the copper wire repeater coil as well as a higher power supply voltage, the passive wireless multi-parameter sensing system finally achieves a maximum readout distance of 13.5 cm.

Sign in / Sign up

Export Citation Format

Share Document