Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles' electromagnetic characteristics. A numerical study of bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate.
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http://dx.doi.org/10.3390/s22072441 | DOI Listing |
Rev Sci Instrum
August 2024
INESC Microsystems and Nanotechnologies (INESC-MN), R. Alves Redol 9, Lisbon 1000-029, Portugal and Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, Lisbon 1049-001, Portugal.
This work shows how the tunnel-effect based magnetoresistance (TMR) technology can be used as a competitive sensing method in electrical current and power processors. The sensor is arranged in a Wheatstone bridge topology, and each magnetoresistance was composed of a series connection of 360 magnetic tunnel junction elements with the following structure (thickness in nm): 100 SiO2/5 Ta/15 Ru/5 Ta/15 Ru/5 Ta/5 Ru/20 IrMn/2 CoFe30/0.85 Ru/2.
View Article and Find Full Text PDFGels
September 2023
Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
Optimized surface-type impedimetric and capacitive proximity sensors have been fabricated on paper substrates by using rubbing-in technology. The orange dye (OD) and silicone glue (SG) composite-gel films were deposited on the zig-zag gap between two aluminum electrodes fixed on a paper (dielectric) substrate. The effect of proximity of various objects (receivers) on the impedance and the capacitance of the sensors was investigated.
View Article and Find Full Text PDFSensors (Basel)
March 2023
Department of Industrial and Information Engineering and Economics, University of L'Aquila, 67100 L'Aquila, Italy.
In this study, a review of second-generation voltage conveyor (VCII) and current conveyor (CCII) circuits for the conditioning of bio signals and sensors is presented. The CCII is the most known current-mode active block, able to overcome some of the limitations of the classical operational amplifier, which provides an output current instead of a voltage. The VCII is nothing more than the dual of the CCII, and for this reason it enjoys almost all the properties of the CCII but also provides an easy-to-read voltage as an output signal.
View Article and Find Full Text PDFSensors (Basel)
May 2022
Department of Industrial and Information Engineering and Economics, University of L'Aquila, 67100 L'Aquila, Italy.
This study reviews second-generation voltage conveyor (VCII)-based read-out circuits for sensors and bioelectrical signal conditioning from existing literature. VCII is the dual circuit of a second-generation current conveyor (CCII), which provides the possibility of processing signals in the current domain while providing output signals in the voltage form. The scope of this paper is to discuss the benefits and opportunities of new VCII-based read-out circuits over traditional ones and bioelectrical signals.
View Article and Find Full Text PDFSensors (Basel)
March 2022
CommSensLab, Universitat Politecnica de Catalunya (UPC), 08034 Barcelona, Spain.
Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles' electromagnetic characteristics. A numerical study of bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres.
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