The Design and Operation of Ultra-Sensitive and Tunable Radio-Frequency Interferometers

Cui, Yan; Wang, Pingshan

doi:10.1109/tmtt.2014.2366134

Cited by 33 publications

(28 citation statements)

References 49 publications

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“…Similar to the highly sensitive and tunable RF interferometers in [18]–[21], two broadband quadrature hybrids (QH) are used for RF probing signal division and combination. Off-chip tuning components, phase shifters (Φ) and attenuators ( R ), are introduced to tune the sensor sensitivity as well as the operating frequency.…”

Section: Slotline-based Rf Sensor Designmentioning

confidence: 99%

See 1 more Smart Citation

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

Cui

Kenworthy

Edidin

et al. 2016

IEEE Trans. Microwave Theory Techn.

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Novel techniques that enable reagent free detection and analysis of single cells are of great interest for the development of biological and medical sciences as well as point-of-care health service technologies. Highly sensitive and broadband radio-frequency (RF) sensors are promising candidates for such a technique. In this work, we present a highly sensitive and tunable RF sensor, which is based on interference processes and built with a 100 nm slotline structure. The highly concentrated RF fields, up to ~1.76×107 V/m, enable strong interactions between Giant unilamellar vesicles (GUVs) and fields for high sensitivity operations. We also provide two modeling approaches to extract cell dielectric properties from measured scattering parameters. GUVs of different molecular compositions are synthesized and analyzed with the RF sensor at ~2 GHz, ~2.5 GHz, and ~2.8 GHz with an initial |S21|min of ~−100 dB. Corresponding GUV dielectric properties are obtained. A one-dimensional scanning of single GUV is also demonstrated.

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Section: Slotline-based Rf Sensor Designmentioning

confidence: 99%

“…These techniques require immobile cells. Recently, we have developed radio-frequency (RF) sensors of different forms with very high and tunable sensitivity over wide frequency ranges [18]–[21]. These sensors promise to be effective tools for the characterization and examination of single cells.…”

Section: Introductionmentioning

confidence: 99%

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

Cui

Kenworthy

Edidin

et al. 2016

IEEE Trans. Microwave Theory Techn.

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“…DNA molecules and their damaged counterparts can be differentiated [13]. The performance of these interferometers is superior to other types of microwave and RF sensors, including those based on whispering gallery mode resonators [14], as discussed in [15]. Nevertheless, the high sensitivity comes with a price, i.e.…”

Section: Introductionmentioning

confidence: 99%

Resonator- and Filter-Induced Slow Waves for High-Sensitivity RF Interferometer Operations

2015

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Resonators and filters have engineered radiofrequency (RF) spectrums and dispersions, which induce slow waves for increased local RF field intensities and prolonged field propagations. When used for sensors, the interactions between RF waves and material-under-test (MUT) can be significantly strengthened due to enhanced RF fields and longer interaction time when compared with uniform transmission lines. In this paper, a microstrip resonator (MR) and a coupled line (CL) filter are designed and incorporated into an interferometer. The obtained results are compared with that of a coplanar waveguidebased interferometer. Both simulated and measured results show that the MR and CL can significantly enhance RF interferometer sensitivity, e.g., by >5 times of frequency shift and up to 40-dB more of transmission coefficient change ∼2 GHz. Further work is needed to fully understand the physical processes and obtain quantitative MUT permittivity properties from the measured scattering parameters.Index Terms-Coplanar waveguide, dielectric spectroscopy, microwave filters, slow wave structure.

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“…Sensitivity improvements are also observed at PGD and SP frequency regions. [5][6][7] in solution. Their design flexibility, tunable sensitivity, and frequency coverage are attractive properties for various sensing applications.…”

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confidence: 99%

“…Radio-frequency (RF) interferometers have been demonstrated for high sensitivity detection and analysis of single cells, 1,2 particles, 3 DNAs, 4 glucose, methanol, and 2-propanel [5][6][7] in solution. Their design flexibility, tunable sensitivity, and frequency coverage are attractive properties for various sensing applications.…”

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confidence: 99%

Two-stage radio-frequency interferometer sensors

Osterberg

Wang

2015

Applied Physics Letters

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We show that simple radio-frequency (RF) interferometers can have slow-wave positive group delay (PGD) or negative group delay (NGD), as well as superluminal propagation (SP) regions, due to a destructive interference process. These properties are easily tunable, which makes RF interferometers unique among systems that have NGD and SP regimes. A two-stage interferometer arrangement, which includes a first stage interferometer in the material-under-test path of a second stage, has significantly improved sensitivity in comparison with a one-stage reference interferometer. With a power divider based first stage and at its maximum NGD frequency, the frequency sensitivity improvement is as high as 7 times. With a quadrature based first stage, the sensitivity is increased by as much as 20 times. Sensitivity improvements are also observed at PGD and SP frequency regions. [5][6][7] in solution. Their design flexibility, tunable sensitivity, and frequency coverage are attractive properties for various sensing applications. Nevertheless, for high sensitivity measurements, the required system dynamic range is exceptionally large, e.g., $120 dB for an effective quality factor of $3 Â 10 6 . 7 As a result, such systems are difficult to use in rugged environments. To help address this problem, different filters and resonators 8-10 are proposed and demonstrated to improve sensitivity for a given dynamic range. With engineered spectrum and dispersion relationship, the probing RF waves in these devices are slowed down with enhanced field intensities, which lead to longer and stronger interactions between RF fields and material-under-test (MUT). The group delays, which are defined as t g ¼ Àdu/ dxj x0 with u is the frequency dependent phase shift and x 0 is the operating frequency, of these filters and resonators are positive. Corresponding group velocities, v g , are lower than the speed of light, c, in the medium, i.e., v g < c.In this work, we show that an RF interferometer can be incorporated into a second one to form a two-stage interferometer to achieve up to 20-times higher frequency sensitivity, compared with one-stage interferometers. The improvements are better than that with filters and resonators. [8][9][10] We also show that a single stage interferometer has negative group delays (NGDs), i.e., negative group velocities (NGVs), and superluminal propagation (SP) regimes. Such abnormal electromagnetic properties have been reported in a few other structures and circuits. [11][12][13][14] In RF interferometers, these properties occur around the operating frequency points and are caused by destructive interference of two traveling waves at the output port. The process is similar to that at the dark port of a Mach-Zehnder interferometer. 13 A simple model shows that loss or reflection is not necessary for the RF interferometer to exhibit those properties. At the same time, large positive group delays (PGDs) can be easily obtained. The achievable NGD, slow wave PGD, and SP levels can be easily tuned. Such tunability is not ...

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The Design and Operation of Ultra-Sensitive and Tunable Radio-Frequency Interferometers

Cited by 33 publications

References 49 publications

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

Resonator- and Filter-Induced Slow Waves for High-Sensitivity RF Interferometer Operations

Two-stage radio-frequency interferometer sensors

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