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Fulltext RF Remote Blood Glucose Sensor and a Microfluidic Vascular Phantom for Sensor Validation

Yunos MFAM, Manczak R, Guines C, Mansor AFM, Mak WC, Khan S, et al.

Biosensors (Basel), 2021 Dec 03;11(12).
PMID: 34940251 DOI: 10.3390/bios11120494

Diabetes has become a major health problem in society. Invasive glucometers, although precise, only provide discrete measurements at specific times and are unsuitable for long-term monitoring due to the injuries caused on skin and the prohibitive cost of disposables. Remote, continuous, self-monitoring of blood sugar levels allows for active and better management of diabetics. In this work, we present a radio frequency (RF) sensor based on a stepped impedance resonator for remote blood glucose monitoring. When placed on top of a human hand, this RF interdigital sensor allows detection of variation in blood sugar levels by monitoring the changes in the dielectric constant of the material underneath. The designed stepped impedance resonator operates at 3.528 GHz with a Q factor of 1455. A microfluidic device structure that imitates the blood veins in the human hand was fabricated in PDMS to validate that the sensor can measure changes in glucose concentrations. To test the RF sensor, glucose solutions with concentrations ranging from 0 to 240 mg/dL were injected into the fluidic channels and placed underneath the RF sensor. The shifts in the resonance frequencies of the RF sensor were measured using a network analyzer via its S11 parameters. Based on the change in resonance frequencies, the sensitivity of the biosensor was found to be 264.2 kHz/mg·dL-1 and its LOD was calculated to be 29.89 mg/dL.

Matched MeSH terms: Radio Waves
Upgrading producer gas quality from rubber wood gasification in a radio frequency tar thermocatalytic treatment reactor

Anis S, Zainal ZA

Bioresour Technol, 2013 Dec;150:328-37.
PMID: 24185417 DOI: 10.1016/j.biortech.2013.10.010

This study focused on improving the producer gas quality using radio frequency (RF) tar thermocatalytic treatment reactor. The producer gas containing tar, particles and water was directly passed at a particular flow rate into the RF reactor at various temperatures for catalytic and thermal treatments. Thermal treatment generates higher heating value of 5.76 MJ Nm(-3) at 1200°C. Catalytic treatments using both dolomite and Y-zeolite provide high tar and particles conversion efficiencies of about 97% on average. The result also showed that light poly-aromatic hydrocarbons especially naphthalene and aromatic compounds particularly benzene and toluene were still found even at higher reaction temperatures. Low energy intensive RF tar thermocatalytic treatment was found to be effective for upgrading the producer gas quality to meet the end user requirements and increasing its energy content.

Matched MeSH terms: Radio Waves*
Fulltext Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats

Narayanan SN, Kumar RS, Potu BK, Nayak S, Bhat PG, Mailankot M

Ups. J. Med. Sci., 2010 May;115(2):91-6.
PMID: 20095879 DOI: 10.3109/03009730903552661

The interaction of mobile phone radio-frequency electromagnetic radiation (RF-EMR) with the brain is a serious concern of our society.

Matched MeSH terms: Radio Waves*
Fulltext Non-ionizing radiation exposure causing ill-health and alopecia areata

Isa AR, Noor M

Med J Malaysia, 1991 Sep;46(3):235-8.
PMID: 1839918

Three cases of occupational exposure to radio-frequency and microwave radiation were seen at the out-patient clinic, Hospital Universiti Sains Malaysia. They presented with run-down symptoms of neck strain associated with throbbing headache, irritability, loss of appetite, fatigue, memory difficulties, and numbness of extremities. They also presented with alopecia areata which is felt to be causally linked to the radiation exposure.

Study site: Outpatient clinic Hospital Universiti Sains Malaysia (HUSM)

Matched MeSH terms: Radio Waves/adverse effects*
Risk Communication Strategies for Possible Health Risks From Radio-Frequency Electromagnetic Fields (RF-EMF) Emission by Telecommunication Structures

Fernandez PR, Ng KH, Kaur S

Health Phys, 2019 06;116(6):835-839.
PMID: 30844902 DOI: 10.1097/HP.0000000000001037

There is widespread anxiety and speculation about RF-EMF emissions by telecommunication base stations and structures, as it is perceived by some to be unsafe and a threat to public health. Scientists, medical experts, politicians, journalists, and mobile telecommunication company specialists are involved in an active debate on whether people are immune to RF or if we are gambling with our future. Interviews with 31 individuals from 7 stakeholder groups in Malaysia reveal that the residents' main concerns are that the telecommunication companies do not follow guidelines and as a result the telecommunication structures are constructed close to their homes, which they perceive as a threat to public health. Some residents also do not want these structures because of cultural reasons, while some are jealous over rental income received by the landlords. Meanwhile, the authorities entrusted with safe-guarding public health are involved in a blame game as there is no agency that is clearly in charge. The interviews also highlight that the current risk communication initiatives are more reactive rather than proactive, and that the authorities do not speak in one voice. Based on the outcome of the interviews, eleven recommendations are formulated to improve risk communication initiatives in Malaysia. The recommendations stress on repairing, building, and strengthening trust, because trust in agencies, along with credibility, determines risk communication initiatives' effectiveness. These strategies can also be effectively replicated across regions to deal with contestations over RF-EMF emissions and the impact on health.

Matched MeSH terms: Radio Waves/adverse effects*
Fulltext Wireless displacement sensing of micromachined spiral-coil actuator using resonant frequency tracking

Ali MS, AbuZaiter A, Schlosser C, Bycraft B, Takahata K

Sensors (Basel), 2014 Jul 10;14(7):12399-409.
PMID: 25014100 DOI: 10.3390/s140712399

This paper reports a method that enables real-time displacement monitoring and control of micromachined resonant-type actuators using wireless radiofrequency (RF). The method is applied to an out-of-plane, spiral-coil microactuator based on shape-memory-alloy (SMA). The SMA spiral coil forms an inductor-capacitor resonant circuit that is excited using external RF magnetic fields to thermally actuate the coil. The actuation causes a shift in the circuit's resonance as the coil is displaced vertically, which is wirelessly monitored through an external antenna to track the displacements. Controlled actuation and displacement monitoring using the developed method is demonstrated with the microfabricated device. The device exhibits a frequency sensitivity to displacement of 10 kHz/µm or more for a full out-of-plane travel range of 466 µm and an average actuation velocity of up to 155 µm/s. The method described permits the actuator to have a self-sensing function that is passively operated, thereby eliminating the need for separate sensors and batteries on the device, thus realizing precise control while attaining a high level of miniaturization in the device.

Matched MeSH terms: Radio Waves
Fulltext Effects of low-powered RF sweep between 0.01-20 GHz on female Aedes Aegypti mosquitoes: A collective behaviour analysis

Poh AH, Moghavvemi M, Shafiei MM, Leong CS, Lau YL, Mahamd Adikan FR, et al.

PLoS One, 2017;12(6):e0178766.
PMID: 28582398 DOI: 10.1371/journal.pone.0178766

There are many products claiming to be an electronic solution towards repelling mosquitoes. Several reviews were published in debunking these claims. However, there is a lack of a systematic study on effects of electromagnetic (EM) or more specifically, radio frequency (RF) waves against mosquitoes due to the conclusions made in those years. Therefore, we attempt to establish a fundamental study on female Aedes Aegypti (Linnaeus) mosquitoes by quantifying the collective behavior of the mosquitoes against a continuous stream of low-powered RF signals via a broadband horn antenna using image processing methods. By examining the average lateral and vertical positions of the mosquitoes versus frequency and time, the data shows negligible consistency in the reactions of the mosquitoes toward the different frequencies ranging from 10 to 20,000.00 MHz, with a step of 10 MHz. This was done by examining 33 hours of spatiotemporal data, which was divided into three sessions. All three sessions showed totally different convolutions in the positions in arbitrary units based on the raster scan of the image processing output. Several frequencies apparently showed up to 0.2-70% shift in both lateral and vertical components along the spectrum, without repeatability for all three sessions. This study contributes to the following: A pilot study for establishing the collective effects of RF against mosquitoes, open-source use, and finally a low-cost and easily adaptable platform for the study of EM effects against any insects.

Matched MeSH terms: Radio Waves
Wirelessly activated device with an integrated ionic polymer metal composite (IPMC) cantilever valve for targeted drug delivery

Cheong HR, Nguyen NT, Khaw MK, Teoh BY, Chee PS

Lab Chip, 2018 10 09;18(20):3207-3215.
PMID: 30229248 DOI: 10.1039/c8lc00776d

This paper reports a wirelessly powered ionic polymer-metal composite (IPMC) soft actuator operated by external radio frequency (RF) magnetic fields for targeted drug delivery. A 183 μm thick IPMC cantilever valve was fitted with an embedded LC resonant circuit to wirelessly control the actuator when the field frequency is tuned to its resonant frequency of approximately 25 MHz. Experimental characterization of the fabricated actuator showed a cumulative cantilever deflection of 160 μm for three repeated RF ON-OFF cycles at 0.6 W input power. The device was loaded with a dye solution and immersed in DI water to demonstrate wireless drug release. The qualitative result shows the successful release of the dye solution from the device reservoir. The release rate can be controlled by tuning the RF input power. We achieved a maximum average release rate of ∼0.1 μl s-1. We further conducted an in vitro study with human tumor cells (HeLa) to demonstrate the proof of concept of the developed device. The experiments show promising results towards the intended drug delivery application.

Matched MeSH terms: Radio Waves
Effects of the nitric acid concentrations on the etching process, structural and optical properties of porous zinc oxide thin films

C.G. Ching, Leonard Lu, C.I. Ang, P.K. Ooi, S.S. Ng, Z. Hassan, et al.

Sains Malaysiana, 2013;42:1327-1332.

The present study reports on the fabrication of porous zinc oxide by wet chemical etching. ZnO thin films were deposited via radio-frequency magnetron sputtering on p-type silicon with (111) preferred orientation. The etchants used in the present work were 0.1% and 1.0% nitric acid (HNO3) solutions. ZnO were etched at various times and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy to allow the examination of their structural and optical properties. The XRD results revealed that the intensity of ZnO(002) decreased when the thin films were etched in varying HNO3 concentrations over different periods of time. The above observation is attributed to the dissolution of the ZnO(002). The SEM images showed that the thickness of the ZnO layers decreased over the etching time, which resulted from the isotropic etching by the HNO3 solution. The PL emission intensity initially increased with increasing etching time. However, with further etching of the samples, the PL spectra showed a decreasing trend in intensity as a result of the decrease in the surface-to-volume ratio. All results lead to the conclusion that 1.0% HNO3 has the capability to change the ZnO surface significantly.

Matched MeSH terms: Radio Waves
Effect of radio frequency power on a-cnx film properties and its performance as humidity sensors

Rozidawati Awang, Noorain Purhanudin, Nur Sakinah Salman

Sains Malaysiana, 2018;47:2863-2867.

A series of amorphous carbon nitride (a-CNx) thin films were deposited on silicon (111) substrates using a home-built
radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) system. The a-CNx thin films were deposited
from a mixture of a fixed flow-rate of ethane (C2
H6
, 20 sccm) and nitrogen (N2
, 47 sccm) gases with varying RF power. A
higher ratio of C to H (C to H ratio is 1:3) atoms in C2
H6
as compared to the ratio in methane (CH4
) gas (C to H ratio is
1:4) is expected to produce an interesting effect to the film properties as humidity sensor. The characterization techniques
used to determine the morphology and chemical bonding of the thin films are field emission scanning electron microscopy
(FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The variation of morphology and the existence
of nitrile band in these samples are correlated with the electrical properties of a-CNx thin films. Using humidity sensing
system, the sensing performance of the samples was examined. It was found that the response of sensors towards the
percentage of relative humidity (% RH) change is good resistive responses and good repeatability. The sensitivity of the
prepared a-CNx thin films is significantly higher (up to 79%) as compared to previous studies using CH4
or acetylene as
precursor gas. Based on these results, the properties and the sensitivity of the a-CNx thin films towards humidity can be
tailored by using an appropriate precursor gases and deposition parameters.

Matched MeSH terms: Radio Waves
Fulltext A low power and low ripple CMOS high voltage generator for RFID transponder EEPROM

Rahman LF, Marufuzzaman M, Alam L, Sidek LM, Reaz MBI

PLoS One, 2020;15(2):e0225408.
PMID: 32023244 DOI: 10.1371/journal.pone.0225408

A high-voltage generator (HVG) is an essential part of a radio frequency identification electrically erasable programmable read-only memory (RFID-EEPROM). An HVG circuit is used to generate a regulated output voltage that is higher than the power supply voltage. However, the performance of the HVG is affected owing to the high-power dissipation, high-ripple voltage and low-pumping efficiency. Therefore, a regulator circuit consists of a voltage divider, comparator and a voltage reference, which are respectively required to reduce the ripple voltage, increase pumping efficiency and decrease the power dissipation of the HVG. Conversely, a clock driving circuit consists of the current-starved ring oscillator (CSRO), and the non- overlapping clock generator is required to drive the clock signals of the HVG circuit. In this study, the Mentor Graphics EldoSpice software package is used to design and simulate the HVG circuitry. The results showed that the designed CSRO dissipated only 4.9 μW at 10.2 MHz and that the phase noise was only -119.38 dBc/Hz at 1 MHz. Moreover, the proposed charge pump circuit was able to generate a maximum VPP of 13.53 V and it dissipated a power of only 31.01 μW for an input voltage VDD of 1.8 V. After integrating all the HVG modules, the results showed that the regulated HVG circuit was also able to generate a higher VPP of 14.59 V, while the total power dissipated was only 0.12 mW with a chip area of 0.044 mm2. Moreover, the HVG circuit produced a pumping efficiency of 90% and reduced the ripple voltage to <4 mV. Therefore, the integration of all the proposed modules in HVG ensured low-ripple programming voltages, higher pumping efficiency, and EEPROMs with lower power dissipation, and can be extensively used in low-power applications, such as in non-volatile memory, radiofrequency identification transponders, on-chip direct current DC-DC converters.

Matched MeSH terms: Radio Waves
A low cost solution for post-biopsy complications using available RFA generator and coaxial core biopsy needle

Azlan CA, Mohd Nasir NF, Saifizul AA, Faizul MS, Ng KH, Abdullah BJ

Australas Phys Eng Sci Med, 2007 Dec;30(4):288-91.
PMID: 18274069

Percutaneous image-guided needle biopsy is typically performed in highly vascular organs or in tumours with rich macroscopic and microscopic blood supply. The main risks related to this procedure are haemorrhage and implantation of tumour cells in the needle tract after the biopsy needle is withdrawn. From numerous conducted studies, it was found that heating the needle tract using alternating current in radiofrequency (RF) range has a potential to minimize these effects. However, this solution requires the use of specially designed needles, which would make the procedure relatively expensive and complicated. Thus, we propose a simple solution by using readily available coaxial core biopsy needles connected to a radiofrequency ablation (RFA) generator. In order to do so, we have designed and developed an adapter to interface between these two devices. For evaluation purpose, we used a bovine liver as a sample tissue. The experimental procedure was done to study the effect of different parameter settings on the size of coagulation necrosis caused by the RF current heating on the subject. The delivery of the RF energy was varied by changing the values for delivered power, power delivery duration, and insertion depth. The results showed that the size of the coagulation necrosis is affected by all of the parameters tested. In general, the size of the region is enlarged with higher delivery of RF power, longer duration of power delivery, and shallower needle insertion and become relatively constant after a certain value. We also found that the solution proposed provides a low cost and practical way to minimizes unwanted post-biopsy effects.

Matched MeSH terms: Radio Waves/therapeutic use*
Radiofrequency electromagnetic radiation-induced behavioral changes and their possible basis

Narayanan SN, Jetti R, Kesari KK, Kumar RS, Nayak SB, Bhat PG

Environ Sci Pollut Res Int, 2019 Oct;26(30):30693-30710.
PMID: 31463749 DOI: 10.1007/s11356-019-06278-5

The primary objective of mobile phone technology is to achieve communication with any person at any place and time. In the modern era, it is impossible to ignore the usefulness of mobile phone technology in cases of emergency as many lives have been saved. However, the biological effects they may have on humans and other animals have been largely ignored and not been evaluated comprehensively. One of the reasons for this is the speedy uncontrollable growth of this technology which has surpassed our researching ability. Initiated with the first generation, the mobile telephony currently reaches to its fifth generation without being screened extensively for any biological effects that they may have on humans or on other animals. Mounting evidences suggest possible non-thermal biological effects of radiofrequency electromagnetic radiation (RF-EMR) on brain and behavior. Behavioral studies have particularly concentrated on the effects of RF-EMR on learning, memory, anxiety, and locomotion. The literature analysis on behavioral effects of RF-EMR demonstrates complex picture with conflicting observations. Nonetheless, numerous reports suggest a possible behavioral effect of RF-EMR. The scientific findings about this issue are presented in the current review. The possible neural and molecular mechanisms for the behavioral effects have been proposed in the light of available evidences from the literature.

Matched MeSH terms: Radio Waves*
Radio frequency electromagnetic radiation (RF-EMR) from GSM (0.9/1.8GHz) mobile phones induces oxidative stress and reduces sperm motility in rats

Mailankot M, Kunnath AP, Jayalekshmi H, Koduru B, Valsalan R

Clinics (Sao Paulo), 2009;64(6):561-5.
PMID: 19578660

INTRODUCTION: Mobile phones have become indispensable in the daily lives of men and women around the globe. As cell phone use has become more widespread, concerns have mounted regarding the potentially harmful effects of RF-EMR from these devices.
OBJECTIVE: The present study was designed to evaluate the effects of RF-EMR from mobile phones on free radical metabolism and sperm quality.
MATERIALS AND METHODS: Male albino Wistar rats (10-12 weeks old) were exposed to RF-EMR from an active GSM (0.9/1.8 GHz) mobile phone for 1 hour continuously per day for 28 days. Controls were exposed to a mobile phone without a battery for the same period. The phone was kept in a cage with a wooden bottom in order to address concerns that the effects of exposure to the phone could be due to heat emitted by the phone rather than to RF-EMR alone. Animals were sacrificed 24 hours after the last exposure and tissues of interest were harvested.
RESULTS: One hour of exposure to the phone did not significantly change facial temperature in either group of rats. No significant difference was observed in total sperm count between controls and RF-EMR exposed groups. However, rats exposed to RF-EMR exhibited a significantly reduced percentage of motile sperm. Moreover, RF-EMR exposure resulted in a significant increase in lipid peroxidation and low GSH content in the testis and epididymis.
CONCLUSION: Given the results of the present study, we speculate that RF-EMR from mobile phones negatively affects semen quality and may impair male fertility.

Matched MeSH terms: Radio Waves/adverse effects*
Fulltext Automatic frequency controller for power amplifiers used in bio-implanted applications: issues and challenges

Hannan MA, Hussein HA, Mutashar S, Samad SA, Hussain A

Sensors (Basel), 2014;14(12):23843-70.
PMID: 25615728 DOI: 10.3390/s141223843

With the development of communication technologies, the use of wireless systems in biomedical implanted devices has become very useful. Bio-implantable devices are electronic devices which are used for treatment and monitoring brain implants, pacemakers, cochlear implants, retinal implants and so on. The inductive coupling link is used to transmit power and data between the primary and secondary sides of the biomedical implanted system, in which efficient power amplifier is very much needed to ensure the best data transmission rates and low power losses. However, the efficiency of the implanted devices depends on the circuit design, controller, load variation, changes of radio frequency coil's mutual displacement and coupling coefficients. This paper provides a comprehensive survey on various power amplifier classes and their characteristics, efficiency and controller techniques that have been used in bio-implants. The automatic frequency controller used in biomedical implants such as gate drive switching control, closed loop power control, voltage controlled oscillator, capacitor control and microcontroller frequency control have been explained. Most of these techniques keep the resonance frequency stable in transcutaneous power transfer between the external coil and the coil implanted inside the body. Detailed information including carrier frequency, power efficiency, coils displacement, power consumption, supplied voltage and CMOS chip for the controllers techniques are investigated and summarized in the provided tables. From the rigorous review, it is observed that the existing automatic frequency controller technologies are more or less can capable of performing well in the implant devices; however, the systems are still not up to the mark. Accordingly, current challenges and problems of the typical automatic frequency controller techniques for power amplifiers are illustrated, with a brief suggestions and discussion section concerning the progress of implanted device research in the future. This review will hopefully lead to increasing efforts towards the development of low powered, highly efficient, high data rate and reliable automatic frequency controllers for implanted devices.

Matched MeSH terms: Radio Waves
Fulltext Analysis of glass-reinforced epoxy material for radio frequency resonator

Zaman MR, Islam MT, Misran N, Yatim B

ScientificWorldJournal, 2014;2014:831435.
PMID: 24977230 DOI: 10.1155/2014/831435

A radio frequency (RF) resonator using glass-reinforced epoxy material for C and X band is proposed in this paper. Microstrip line technology for RF over glass-reinforced epoxy material is analyzed. Coupling mechanism over RF material and parasitic coupling performance is explained utilizing even and odd mode impedance with relevant equivalent circuit. Babinet's principle is deployed to explicate the circular slot ground plane of the proposed resonator. The resonator is designed over four materials from different backgrounds which are glass-reinforced epoxy, polyester, gallium arsenide (GaAs), and rogers RO 4350B. Parametric studies and optimization algorithm are applied over the geometry of the microstrip resonator to achieve dual band response for C and X band. Resonator behaviors for different materials are concluded and compared for the same structure. The final design is fabricated over glass-reinforced epoxy material. The fabricated resonator shows a maximum directivity of 5.65 dBi and 6.62 dBi at 5.84 GHz and 8.16 GHz, respectively. The lowest resonance response is less than -20 dB for C band and -34 dB for X band. The resonator is prototyped using LPKF (S63) drilling machine to study the material behavior.

Matched MeSH terms: Radio Waves
Fulltext Development of simple designs of multitip probe diagnostic systems for RF plasma characterization

Naz MY, Shukrullah S, Ghaffar A, Rehman NU

ScientificWorldJournal, 2014;2014:279868.
PMID: 24683326 DOI: 10.1155/2014/279868

Multitip probes are very useful diagnostics for analyzing and controlling the physical phenomena occurring in low temperature discharge plasmas. However, DC biased probes often fail to perform well in processing plasmas. The objective of the work was to deduce simple designs of DC biased multitip probes for parametric study of radio frequency plasmas. For this purpose, symmetric double probe, asymmetric double probe, and symmetric triple probe diagnostic systems and their driving circuits were designed and tested in an inductively coupled plasma (ICP) generated by a 13.56 MHz radio frequency (RF) source. Using I-V characteristics of these probes, electron temperature, electron number density, and ion saturation current was measured as a function of input power and filling gas pressure. An increasing trend was noticed in electron temperature and electron number density for increasing input RF power whilst a decreasing trend was evident in these parameters when measured against filling gas pressure. In addition, the electron energy probability function (EEPF) was also studied by using an asymmetric double probe. These studies confirmed the non-Maxwellian nature of the EEPF and the presence of two groups of the energetic electrons at low filling gas pressures.

Matched MeSH terms: Radio Waves
Analysis on the effect of the distances and inclination angles between human head and mobile phone on SAR

Hossain MI, Faruque MR, Islam MT

Prog Biophys Mol Biol, 2015 Nov;119(2):103-10.
PMID: 25863147 DOI: 10.1016/j.pbiomolbio.2015.03.008

The aim of this paper is to investigate the effects of the distances between the human head and internal cellular device antenna on the specific absorption rate (SAR). This paper also analyzes the effects of inclination angles between user head and mobile terminal antenna on SAR values. The effects of the metal-glass casing of mobile phone on the SAR values were observed in the vicinity of the human head model. Moreover, the return losses were investigated in all cases to mark antenna performance. This analysis was performed by adopting finite-difference time-domain (FDTD) method on Computer Simulation Technology (CST) Microwave Studio. The results indicate that by increasing the distance between the user head and antenna, SAR values are decreased. But the increase in inclination angle does not reduce SAR values in all cases. Additionally, this investigation provides some useful indication for future design of low SAR mobile terminal antenna.

Matched MeSH terms: Radio Waves

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