Due to the recent pandemic caused by coronavirus disease 2019 (COVID-19), the lateral flow immunoassay used for its rapid antigen test is more popular than ever before. However, the history of the ...lateral flow immunoassay is about 60 years old, and its original purpose of use, such as a COVID-19 rapid antigen test or a pregnancy test, was the qualitative detection of a target analyte. Recently, the demand for quantitative analysis of lateral flow immunoassays is increasing in various fields. Lateral flow immunoassays for quantitative detection using various materials and sensor technologies are being introduced, and readers for analyzing them are being developed. Quantitative analysis readers are highly anticipated for their future development in line with technological advancements such as optical, magnetic field, photothermal, and electrochemical sensors and trends such as weight reduction, miniaturization, and cost reduction of systems. In addition, the sensing, processing, and communication functions of portable personal devices such as smartphones can be used as tools for the quantitative analysis of lateral flow immunoassays. As a result, lateral flow immunoassays can efficiently achieve the goal of rapid diagnosis by point-of-care testing. Readers used for the quantification of lateral flow immunoassays were classified according to the adopted sensor technology, and the research trends in each were reviewed in this paper. The development of a quantitative analysis system was often carried out in the assay aspect, so not only the readers but also the assay development cases were reviewed if necessary. In addition, systems for quantitative analysis of COVID-19, which have recently been gaining importance, were introduced as a separate section.
A radio frequency identification system can establish a communication between tags and readers through a wireless connection. Due to the optimized coverage of the environment, the readers are placed ...close to each other in this system and hence it is called dense reader environment. The very property of such an environment leads to increase in the probability of occurrence of reader-to-reader and reader-to-tag collisions which consequently come up with decrease in performance of the network. To solve this problem, many various protocols have been proposed of which centralized ones provide higher throughput. Our proposed method can reduce reader-to-reader collision through combining TDMA and FDMA mechanisms and benefiting from sift probability function and fairness. Furthermore, we found that distance comparison between two readers can reduce reader-to-tag collision as well. Our simulations indicate that the proposed method provides better throughput, average waiting time and fairness than existing ones. Our method also supports the mobility of the readers.
Operation principle and design approach of a novel planar end-lire circularly polarized (CP) complementary antenna is proposed. A vertically polarized printed magnetic dipole and a horizontally ...polarized printed dipole are combined on the same substrate, and a planar CP antenna with end-lire beam in parallel with its plane is thus designed. Prototype antennas centered at 5.80 GHz are then fabricated and measured to validate the operation principle and the design approach. The experimental prototype reported that the impedance bandwidth (20 log |S 11 | ( <; -10 dB) is about 1.90%, from 5.75 to 5.86 GHz and the 3-dB axial ratio (AR) bandwidth is about 14.48%, from 5.19 to 6.00 GHz. Therefore, the proposed design is applicable as a low-prolile handheld reader antenna in radio-frequency identilication (RFID) systems.
UHF RFID reader transceiver for Chinese local standard (840-845 MHz and 920-925 MHz), in concord with the protocols of EPC Class-1 Gen-2 and ISO/IEC 18000-6C, is presented. A highly linear RF ...front-end with low flicker noise, an on-chip self-jammer cancellation (SC) circuit with fast time-varying cut-off frequency and a DC-offset cancellation (DCOC) circuit are proposed to deal with the large self-jammer in the receiver. In the presence of 22 dBm PA output power, the receiver achieves a sensitivity of -79 dBm including the 15 dB loss of the directional coupler. A CMOS class-AB PA is integrated in the transmitter, with 22 dBm output power and 35% PAE. The spectrum mask achieves ACPR 1 of -45 dBc and ACPR 2 of -60 dBc . A sigma-delta fractional-N PLL with a single LC VCO is also implemented for good phase noise (-126 dBc/Hz @ 1 MHz offset) and high frequency resolution within 1 kHz. This single-chip is fabricated in a 0.18 standard CMOS process. It occupies a silicon area of 13.5 mm 2 and dissipates 203 mW from a 1.8 V supply voltage when transmitting 7.5 dBm output power.
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