scholarly journals A Wireless, Passive pH Sensor Based on Magnetic Higher-Order Harmonic Fields

2009 ◽  
Vol 3 (2) ◽  
Author(s):  
B. Horton ◽  
E. Tan ◽  
B. Pereles ◽  
K. Ong
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Human Body ◽  
Remote Monitoring ◽  
Higher Order ◽  
Sensing Element ◽  
Dc Magnetic Field ◽  
Harmonic Field ◽  
Field Shift ◽  
Detection Coil

A wireless, passive sensor was fabricated for remote monitoring of chemical analytes in the human body. The sensor was made of a magnetically soft film (sensing element) and a permanent magnetic film (biasing element) sandwiching a reversibly swelling hydrogel. When subjected to a low frequency magnetic AC field, the sensing element generated higher-order harmonic magnetic fields that were detected with a remotely located detection coil. In the presence of a DC magnetic field (biasing field), such as that generated from the biasing element, the pattern of the higher-order harmonic magnetic fields varied, and the magnitude of change (referred to as the harmonic field shift) was proportional to the strength of the biasing field. The hydrogel, which acted as a transducer that converted variations in the chemical concentration into changes in dimensions, physically varied the separation distance between the sensing and the biasing elements. This causes a change in the magnitude of biasing field experienced by the sensing element, thus changing its higher-order harmonic field shift allowing remote measurement of chemical concentrations. The novelty of this sensor was its wireless and passive nature, which allows it to be used inside a human body for long term chemical monitoring. A scaled-up prototype was fabricated and tested to demonstrate the pH monitoring capability of the sensor. The main structure of the prototype sensor was a polycarbonate substrate containing a larger rectangular well of 36mm×8mm×4mm on top of a smaller well of 30mm×5mm×2mm (see Fig. 1). The smaller well was filled with hydrogel made of (poly)vinyl alcohol and (poly)acrylic acid. A commercial magnetoelastic thick film, Metglas 2826MB from Metglas Inc., was attached to the step at the bottom of the larger well and allowed to rest on the hydrogel. The DC magnetic field was provided by an Arnokrome III film (Arnold Magnetic Technologies) of 30mm×6mm attached at the bottom of the sensor structure. The sensor was placed on the detection coil, and its response was measured with a spectrum analyzer while exposed to test solutions of varying pH. The sensor's harmonic field shift, when cycled between pH 7 and pH 3, was measured and plotted in Fig. 2. As shown in the figure, the hydrogel swelled when the sensor was exposed to pH 3, decreasing the harmonic field shift. The response and recovery times of the hydrogel were below 2 minutes. This experiment proves the feasibility of the technology for real-time, remote monitoring of pH. Further work includes improving the response time and sensitivity of the hydrogel, as well as miniaturization of the sensor.

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

Study on the Solidification Structures of Al-Fe-Si Alloy under DC and AC Magnetic Fields

2011 ◽  
Vol 189-193 ◽  
pp. 4477-4482
Author(s):  
Chun Yan Ban ◽  
Xu Zhang ◽  
Peng Qian ◽  
Yi Han ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Chinese Script ◽  
Minor Amount ◽  
Fine Needle ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Conventional Condition ◽  
The Difference ◽  
Al Matrix

The effects of DC and AC magnetic field on the phase composition, morphology and distribution of the ternary Al-Fe-Si alloy were investigated. The solidification structures of the alloy solidified with and without the application of magnetic fields were confirmed by DSC and structural measurements. The results showed that, in this Al-Fe-Si alloy the fine needle-like Al3Fe phase dominated the microstructure at the grain boundaries with the minor amount of Chinese script-like α-AlFeSi. Distribution of Al3Fe phase was almost homogeneous in the volume of the sample when alloy was solidified in the conventional condition. When the DC magnetic field was imposed, distribution of Al3Fe phase was more homogeneous. However, the Al3Fe and α-AlFeSi phases were accumulated towards the center of the sample with the application of the AC magnetic field. This is due to the difference of Lorentz force between Al matrix and iron-containing intermetallics. Furthermore, the amount of Chinese script-like α-AlFeSi was increased remarkably under AC magnetic field.

Analysis of Biological Effect of AC-DC Electromagnetic Fields using the Lorenz Model

2011 ◽  
pp. 31-53
Author(s):  
Malka N. Halgamuge ◽  
Chathurika D. Abeyrathne ◽  
Priyan Mendis
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Electromagnetic Fields ◽  
Biological Effect ◽  
Initial Velocity ◽  
Charged Particles ◽  
Initial Position ◽  
Dc Magnetic Field ◽  
Ac Electric Field

Electromagnetic fields (EMF) are essential to various applications directly involving humans. Fears about the biological effect of exposure to electromagnetic fields drive enormous research into this area. This research generates conflicting results, and consequently, uncertainty regarding possible health effects. This chapter studies a nonlinear Lorenz model describing interactions among charged particles and combined alternating (AC: alternating current) and static (DC: direct current) electromagnetic fields, for various combinations of frequencies, field strengths and relative angle (?) between the AC and DC magnetic fields. We investigate the effect on charged particles of three possible combinations of alternating and static electromagnetic fields: (i) AC electric field and DC magnetic field (ii) AC magnetic field and DC magnetic field (iii) AC electric field and AC and DC magnetic field. Then the behavior of the particle in these fields with different initial conditions and strong directional effects is observed when the angle between AC and DC magnetic fields is varied. The results show that the cyclotron resonance frequency is affected by charged particles’ initial position and initial velocity. Further, we observe strong effects of electric and magnetic fields on a charged particle in a biological cell with initial position and initial velocity.

scholarly journals Fusion and nucleosynthesis by hypervelocity impact using hybrid magnetic fields

2005 ◽  
Vol 23 (2) ◽  
pp. 219-224 ◽  
Author(s):  
ALEXANDRE POZWOLSKI
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hypervelocity Impact ◽  
Mutual Interaction ◽  
High Current ◽  
Fusion Reactions ◽  
Dc Magnetic Field ◽  
Metallic Ring

The electromagnetic acceleration of a metallic ring carrying a high current, combined with the mutual interaction of a concentrical conductor carrying the same current, in the presence of a DC magnetic field, results in a converging beam of particles reaching a velocity above 1000 km/s. Lithium, gold, and uranium rings are considered and transient temperatures ranging from 108to 1010°K are expected. In the presence of deuterium and tritium fusion reactions will occur and the capture of the released neutrons may result in the synthesis of heavier elements. The considered device lends itself to a varied treatment allowing to consider velocities in the range of 2000 km/s.

scholarly journals IoT Based Framework for Remote Monitoring of Heartbeat Alert System by Using Arduino

2020 ◽  
Author(s):  
Sharouq Aamir Mohammed Al-Musheifri ◽  
Syed Ateeq Ahmed
Keyword(s):  
Heart Rate ◽  
Human Body ◽  
Remote Monitoring ◽  
The Body ◽  
Sensing Element ◽  
Alert System ◽  
Medical Department ◽  
On Demand ◽  
New Methods ◽  
Medical Health

The heart is one of the most important organs of the human body. It acts as a pump that circulates the blood, carrying oxygen and nutrients in the body to keep it functioning. Today, several advanced methods have emerged in the field of medicine, which aim to improve the efficiency of the medical services.  And these new methods are akin to a technical identification of the disease with high precision, a new radiological technology and a fashionable identification of medical health. In the medical department, several studies are underway to provide the latest technologies. There are some people suffer from bradycardia or tachycardia. Might their lives are in danger if the patients are alone. In this research paper, a framework is developed to solve and improve equipment that constantly monitors heart rate and prevent casualties due to the heart related problems. The research is done to reduce deaths resulting from irregular heartbeat.  Uneven heart rating which is greater than determined value raises an alert and messages with heart readings are sent to doctors and other related persons. It also provides this information via Bluetooth and exposes it in the Arduino application platform to ensure the information is not corrupted and recalled on demand. Doctor can remotely access the sensing element. For this reason, Arduino-based sensors dealing with these problems are used in this smart application. An Arduino-based sensing element evaluates the patient's heart rate. Coupled with this, doctors remotely follow the patient and take quick action to save patients life.

The effect of DC magnetic field on signal characteristics of magnetic Barkhausen noise

2020 ◽  
Vol 64 (1-4) ◽  
pp. 887-894
Author(s):  
Chengyong Liu ◽  
Erlong Li ◽  
Shiqiang Wang ◽  
Jianbo Wu ◽  
Hui Fang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Peak Position ◽  
Barkhausen Noise ◽  
Magnetic Barkhausen Noise ◽  
Dc Magnetic Field ◽  
Actual Application ◽  
Detection Technology ◽  
Signal Characteristics ◽  
Detection Of Stress

Magnetic Barkhausen Noise (MBN) detection technology shows great potential in the pipeline detection of stress, microstructure, and fatigue damage. However, in actual application, some pipes such as those near power plant are exposed to external magnetic fields or contain remanence. The presence of these magnetic fields will affect MBN features and then influence the testing results. To investigate the effect of DC magnetic field on MBN signal characteristics, theoretical analysis and experimental verification were carried out in this paper. It is found that the intensity and direction of the DC magnetic field have great effects on MBN signal characteristics, including the changes in the energy of MBN signal, the peak position and the shape of MBN signal profile.

Effects of DC and AC Magnetic Fields on Grain Growth in Electrodeposited Nanocrystalline Nickel

2003 ◽  
Vol 788 ◽  
Author(s):  
T. Matsuzaki ◽  
T. Yamada ◽  
K. Jyuami ◽  
S. Tsurekawa ◽  
T. Watanabe ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Grain Growth ◽  
Temperature Region ◽  
Incubation Time ◽  
The Other ◽  
Grain Structure ◽  
Nanocrystalline Nickel ◽  
Magnetic Annealing ◽  
Dc Magnetic Field

ABSTRACTThe effects of DC and AC magnetic fields on grain growth in electrodeposited nanocrystalline nickel were studied. Magnetic annealing was conducted at 573K in the ferromagnetic temperature region and at 693K in the paramagnetic temperature region. Both DC and AC magnetic annealing could enhance the grain growth and produced a homogeneous grain structure at 573K. On the other hand, AC magnetic annealing shortened the incubation time for the late stage abnormal grain growth at 693K in the paramagnetic temperature region, while DC magnetic field could not affect the incubation time.

Effect of DC and AC Magnetic Fields on the Solidification Structure of Commercially Pure Aluminium

2012 ◽  
Vol 583 ◽  
pp. 387-390 ◽  
Author(s):  
Chun Yan Ban ◽  
Dan Dan Jiang ◽  
Lian Liu ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Cooling Rate ◽  
Solidification Structure ◽  
Pure Aluminium ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Commercially Pure

The effect of DC and AC magnetic fields on the macrostructure, morphology and distribution of the iron-containing intermetallics in the commercially pure Al was investigated. It is found that, at a cooling rate of 3°C/min, the grain is very coarse when the alloy solidifies both with and without magnetic fields. Comparing with the sample solidifies without magnetic field, the solidification structure has almost no change when it solidifies under DC magnetic field, while AC magnetic field changes the solidification structure obviously and makes grains show radial columnar crystals. The intermetallics is dominated by long needle-like phase when the sample solidifies under the condition of no magnetic field. Under AC magnetic field, the intermetallics is refined and accumulated towards the center of sample, and the amount of bone-like α-AlFeSi phase is increased remarkably. The mechanism of the effect of magnetic fields was discussed.

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