scholarly journals Noninvasive visualization of electrical conductivity in tissues at the micrometer scale

2021 ◽  
Vol 7 (20) ◽  
pp. eabd1505
Author(s):  
Yuanhui Huang ◽  
Murad Omar ◽  
Weili Tian ◽  
Hernán Lopez-Schier ◽  
Gil Gregor Westmeyer ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Radio Frequency ◽  
Near Field ◽  
Label Free ◽  
Radio Waves ◽  
Direct Absorption ◽  
Invasive Procedures ◽  
Ultrasound Waves ◽  
Micrometer Scale ◽  
Radio Frequency Pulses

Despite its importance in regulating cellular or tissue function, electrical conductivity can only be visualized in tissue indirectly as voltage potentials using fluorescent techniques, or directly with radio waves. These either requires invasive procedures like genetic modification or suffers from limited resolution. Here, we introduce radio-frequency thermoacoustic mesoscopy (RThAM) for the noninvasive imaging of conductivity by exploiting the direct absorption of near-field ultrashort radio-frequency pulses to stimulate the emission of broadband ultrasound waves. Detection of ultrasound rather than radio waves enables micrometer-scale resolutions, over several millimeters of tissue depth. We confirm an imaging resolution of <30 μm in phantoms and demonstrate microscopic imaging of conductivity correlating to physical structures in 1- and 512-cell zebrafish embryos, as well as larvae. These results support RThAM as a promising method for high-resolution, label-free assessment of conductivity in tissues.

The Single-Position Method for Determining the Coordinates of a Radio-Frequency Source in the Near-Field Region

2009 ◽  
Vol 68 (8) ◽  
pp. 687-695
Author(s):  
L. I. Diduk ◽  
V. I. Nikolskii ◽  
S. N. Panychev
Keyword(s):  
Radio Frequency ◽  
Near Field ◽  
Field Region ◽  
Frequency Source

Radio and Electrical Measurements on Glacial Streams

1987 ◽  
Vol 33 (114) ◽  
pp. 239-242
Author(s):  
M. E. R. Walford
Keyword(s):  
Electrical Conductivity ◽  
Water Channel ◽  
Water System ◽  
Low Frequency ◽  
Water Channels ◽  
Radiative Loss ◽  
Radio Waves ◽  
Electrical Measurements ◽  
Water Conductivity ◽  
Glacier Surface

AbstractWe discuss the suggestion that small underwater transmitters might be used to illuminate the interior of major englacial water channels with radio waves. Once launched, the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss. Receivers placed within the channels or at the glacier surface could be used to detect the signals. They would provide valuable information about the connectivity of the water system. The electrical conductivity of the water is of crucial importance. A surface stream on Storglaciären, in Sweden, was found, using a low-frequency technique, to have a conductivity of approximately 4 × 10−4 S m−1. Although this is several hundred times higher than the conductivity of the surrounding glacier ice, the contrast is not sufficient to permit us simply to use electrical conductivity measurements to establish the connectivity of englacial water channels. However, the water conductivity is sufficiently small that, under favourable circumstances, radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel. In a preliminary field experiment, we demonstrated semi quantitatively that radio waves do indeed propagate as expected, at least in surface streams. We conclude that under-water radio transmitters could be of real practical value in the study of the englacial water system, provided that sufficiently robust devices can be constructed. In a subglacial channel, however, we expect the radio range would be much smaller, the environment much harsher, and the technique of less practical value.

scholarly journals Demonstration of an integrated nanophotonic chip-scale alkali vapor magnetometer using inverse design

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yoel Sebbag ◽  
Eliran Talker ◽  
Alex Naiman ◽  
Yefim Barash ◽  
Uriel Levy
Keyword(s):  
Spatial Resolution ◽  
Near Field ◽  
Computer Assisted ◽  
Experimental Characterization ◽  
Optical Isolation ◽  
New Concepts ◽  
On Chip ◽  
The Cost ◽  
Micrometer Scale

AbstractRecently, there has been growing interest in the miniaturization and integration of atomic-based quantum technologies. In addition to the obvious advantages brought by such integration in facilitating mass production, reducing the footprint, and reducing the cost, the flexibility offered by on-chip integration enables the development of new concepts and capabilities. In particular, recent advanced techniques based on computer-assisted optimization algorithms enable the development of newly engineered photonic structures with unconventional functionalities. Taking this concept further, we hereby demonstrate the design, fabrication, and experimental characterization of an integrated nanophotonic-atomic chip magnetometer based on alkali vapor with a micrometer-scale spatial resolution and a magnetic sensitivity of 700 pT/√Hz. The presented platform paves the way for future applications using integrated photonic–atomic chips, including high-spatial-resolution magnetometry, near-field vectorial imaging, magnetically induced switching, and optical isolation.

Near Field Radio-Frequency Electromagnetic Field Exposure of a Western Honey Bee

2021 ◽  
pp. 1-1
Author(s):  
David Toribio ◽  
Wout Joseph ◽  
Arno Thielens
Keyword(s):  
Electromagnetic Field ◽  
Radio Frequency ◽  
Honey Bee ◽  
Near Field ◽  
Field Exposure

scholarly journals Uses of radio emission spectroscopy for non-contact and in situ diagnostics of low pressure radio frequency plasma processing

2021 ◽  
Author(s):  
Rajani K. Vijayaraghavan ◽  
Sean Kelly ◽  
David Coates ◽  
Cezar Gaman ◽  
Niall MacGearailt ◽  
...  
Keyword(s):  
Radio Emission ◽  
Radio Frequency ◽  
Emission Spectroscopy ◽  
Near Field ◽  
Plasma Processing ◽  
Diagnostic Technique ◽  
Primary Source ◽  
Low Pressure ◽  
Chamber Pressure ◽  
Rf Plasma

Abstract We demonstrate that a passive non-contact diagnostic technique, radio emission spectroscopy (RES), provides a sensitive monitor of currents in a low pressure radio frequency (RF) plasma. A near field magnetic loop antenna was used to capture RF emissions from the plasma without perturbing it. The analysis was implemented for a capacitively coupled RF plasma with an RF supply at a frequency of 13.56 MHz. Real-time measurements are captured in scenarios relevant to contemporary challenges faced during semiconductor fabrication (e.g. window coating and wall disturbance). Exploration of the technique for key equipment parameters including applied RF power, chamber pressure, RF bias frequencies and chamber wall cleanliness shows sensitive and repeatable function. In particular, the induced RES signal was found to vary sensitively to pressure changes and we were able to detect pressure and power variations as low as ~2.5 %/mtorr and ~3.5 %/watt, respectively, during the plasma processing during a trial generic plasma process. Finally, we explored the ability of RES to monitor the operation of a multiple frequency low-pressure RF plasma system (f1 = 2 MHz, f2 = 162 MHz) and intermixing products which suggests strongly that the plasma sheaths are the primary source of this non-linear diode mixing effect.

scholarly journals Design and Development Of Lecturer Attendance System Using Radio Frequency Identification (RFID)

2021 ◽  
Vol 10 (1) ◽  
pp. 15-27
Author(s):  
I Gede Sujana Eka Putra ◽  
Anthony Lee ◽  
I Made Tirta Mahayana ◽  
I Gede Agung Wicaksono Dharmayasa
Keyword(s):  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Web Application ◽  
Academic Staff ◽  
Near Field ◽  
Literature Study ◽  
Master Data ◽  
Presence Data ◽  
Frequency Identification ◽  
The University

Lecturer attendance record is required by the university to know the presence of lecturers in teaching in class. In general condition, lecturer attendance is recorded on the attendance sheet, or input to web application accessed on a class computer. However, there are some problems in its implementation so that at the end, lecturer presence is carried out using a manual form where the academic staff needs to re-enter the lecturer attendance data into the applications. Based on the above, the authors designed and developed a lecturer attendance information system to record lecturers' attendance using radio frequency identification technology by implementing a near field communication card (NFC Card). The device used to record and read presence data during lectures, by tapping an Mi-fare NFC card to an NFC reader / writer device. The flow of this research method begins with a literature study of NFC card, observe the flow of lecture attendance process and data recorded into lecturer attendance sheet, analyzing the database design, the system design which has compatible with NFC reader and writer devices, designed system interface and continue to develop system. The result is system consists of master data, system attendance, verification and reporting module. The results show that NFC card implementation is more practical for lecturers in conducting lecture attendance and NFC card could be tapped out into an NFC device at a maximum distance up to 7 cm with the reading angle relative to NFC reader/writer with range 00 until 300 can read NFC Card.

scholarly journals High precision epidermal radio frequency antenna via nanofiber network for wireless stretchable multifunction electronics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yufei Zhang ◽  
Zhihao Huo ◽  
Xiandi Wang ◽  
Xun Han ◽  
Wenqiang Wu ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Near Field ◽  
Transmission Efficiency ◽  
Stretchable Electronics ◽  
Information Communication ◽  
Long Distance ◽  
Human Machine Interaction ◽  
Natural Systems ◽  
Content Recognition ◽  
Healthcare Monitoring

Abstract Recently, stretchable electronics combined with wireless technology have been crucial for realizing efficient human-machine interaction. Here, we demonstrate highly stretchable transparent wireless electronics composed of Ag nanofibers coils and functional electronic components for power transfer and information communication. Inspired by natural systems, various patterned Ag nanofibers electrodes with a net structure are fabricated via using lithography and wet etching. The device design is optimized by analyzing the quality factor and radio frequency properties of the coil, considering the effects of strain. Particularly, the wireless transmission efficiency of a five-turn coil drops by approximately only 50% at 10 MHz with the strain of 100%. Moreover, various complex functional wireless electronics are developed using near-field communication and frequency modulation technology for applications in content recognition and long-distance transmission (>1 m), respectively. In summary, the proposed device has considerable potential for applications in artificial electronic skins, human healthcare monitoring and soft robotics.

scholarly journals Aptamer Functionalized Lipid Multilayer Gratings for Label-Free Analyte Detection

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2433
Author(s):  
Plengchart Prommapan ◽  
Nermina Brljak ◽  
Troy W. Lowry ◽  
David Van Winkle ◽  
Steven Lenhert
Keyword(s):  
Lipid Composition ◽  
Optical Biosensor ◽  
Optical Signal ◽  
Dna Aptamer ◽  
Critical Parameters ◽  
Label Free ◽  
Scale Thickness ◽  
Label Free Detection ◽  
Analyte Detection ◽  
Micrometer Scale

Lipid multilayer gratings are promising optical biosensor elements that are capable of transducing analyte binding events into changes in an optical signal. Unlike solid state transducers, reagents related to molecular recognition and signal amplification can be incorporated into the lipid grating ink volume prior to fabrication. Here we describe a strategy for functionalizing lipid multilayer gratings with a DNA aptamer for the protein thrombin that allows label-free analyte detection. A double cholesterol-tagged, double-stranded DNA linker was used to attach the aptamer to the lipid gratings. This approach was found to be sufficient for binding fluorescently labeled thrombin to lipid multilayers with micrometer-scale thickness. In order to achieve label-free detection with the sub-100 nm-thick lipid multilayer grating lines, the binding affinity was improved by varying the lipid composition. A colorimetric image analysis of the light diffracted from the gratings using a color camera was then used to identify the grating nanostructures that lead to an optimal signal. Lipid composition and multilayer thickness were found to be critical parameters for the signal transduction from the aptamer functionalized lipid multilayer gratings.

Sign in / Sign up

Export Citation Format

Share Document