Backscattering measurement from a single microdroplet

Lee, Jungwoo; Chang, Jin Ho; Jeong, Jong Seob; Lee, Changyang; Teh, Shia-Yen; Lee, A; Shung, K. Kirk

doi:10.1109/tuffc.2011.1882

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…To demonstrate the capability of the proposed method to capture one micro-sized particle and measure its physical properties simultaneously, we measured the IB coefficient of the trapped polystyrene microsphere because this coefficient is related to the size of a particle 38 , 39 . For this experiment, the monocycle pulses with a length of 6.7 ns and a magnitude of 50 V at a PRF of 167 kHz were used for simultaneous capture and measurement.…”

Section: Resultsmentioning

confidence: 99%

“…An IB coefficient is defined as the ratio of backscattered ultrasound energy from a scatterer volume to the one from a flat quartz target. This is expressed as 39 where R(f) and V(f) are, respectively, the frequency spectrum of the recorded backscattered signals from the quartz target and the trapped objects (particles or cells). Moreover, and represent the centre frequency and the −6 dB bandwidth of R(f), respectively.…”

Section: Methodsmentioning

confidence: 99%

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Label-free analysis of the characteristics of a single cell trapped by acoustic tweezers

Kim

Park

Lim

et al. 2017

Sci Rep

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Single-cell analysis is essential to understand the physical and functional characteristics of cells. The basic knowledge of these characteristics is important to elucidate the unique features of various cells and causative factors of diseases and determine the most effective treatments for diseases. Recently, acoustic tweezers based on tightly focused ultrasound microbeam have attracted considerable attention owing to their capability to grab and separate a single cell from a heterogeneous cell sample and to measure its physical cell properties. However, the measurement cannot be performed while trapping the target cell, because the current method uses long ultrasound pulses for grabbing one cell and short pulses for interrogating the target cell. In this paper, we demonstrate that short ultrasound pulses can be used for generating acoustic trapping force comparable to that with long pulses by adjusting the pulse repetition frequency (PRF). This enables us to capture a single cell and measure its physical properties simultaneously. Furthermore, it is shown that short ultrasound pulses at a PRF of 167 kHz can trap and separate either one red blood cell or one prostate cancer cell and facilitate the simultaneous measurement of its integrated backscattering coefficient related to the cell size and mechanical properties.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Label-free analysis of the characteristics of a single cell trapped by acoustic tweezers

Kim

Park

Lim

et al. 2017

Sci Rep

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“…The experimentally measured integrated backscatter was found to be in good agreement with theoretically calculated values from the T-matrix method [17], suggesting that this approach may be employed as a means for quantitatively measuring ultrasonic backscattering from a single microparticle. High-frequency ultrasound was subsequently employed for microdroplet sensing and sorting in a microfluidic device [7].…”

Section: Introductionmentioning

confidence: 65%

Ultrasonic scattering measurements of a live single cell at 86 MHz

Lee

Jung

Lam

et al. 2015

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Cell separation and sorting techniques have been employed biomedical applications such as cancer diagnosis and cell gene expression analysis. The capability to accurately measure ultrasonic scattering properties from cells is crucial in making an ultrasonic cell sorter a reality if ultrasound scattering is to be used as the sensing mechanism as well. To assess the performance of sensing and identifying live single cells with high-frequency ultrasound, an 86-MHz lithium niobate press-focused single-element acoustic transducer was used in a high-frequency ultrasound scattering measurement system that was custom designed and developed for minimizing noise and allowing better mobility. Peak-to-peak echo amplitude, integrated backscatter (IB) coefficient, spectral parameters including spectral slope and intercept, and midband fit from spectral analysis of the backscattered echoes were measured and calculated from a live single cell of two different types on an agar surface: leukemia cells (K562 cells) and red blood cells (RBCs). The amplitudes of echo signals from K562 cells and RBCs were 48.25 ± 11.98 mVpp and 56.97 ± 7.53 mVpp, respectively. The IB coefficient was −89.39 ± 2.44 dB for K562 cells and −89.00 ± 1.19 dB for RBCs. The spectral slope and intercept were 0.30 ± 0.19 dB/MHz and −56.07 ± 17.17 dB, respectively, for K562 cells and 0.78 ± 0.092 dB/MHz and −98.18 ± 8.80 dB, respectively, for RBCs. Midband fits of K562 cells and RBCs were −31.02 ± 3.04 dB and −33.51 ± 1.55 dB, respectively. Acoustic cellular discrimination via these parameters was tested by Student’s t-test. Their values, except for the IB value, showed statistically significant difference (p < 0.001). This paper reports for the first time that ultrasonic scattering measurements can be made on a live single cell with a highly focused high-frequency ultrasound microbeam at 86 MHz. These results also suggest the feasibility of ultrasonic scattering as a sensing mechanism in the development of ultrasonic cell sorters.

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“…In addition to skin disease treatment, we believe that another potential application of the proposed method is to generate a microbeam for acoustic tweezers [ 26 , 27 , 28 ]. This is because the acoustic tweezers also require the tight focus of ultrasound.…”

Section: Discussionmentioning

confidence: 99%

Design and Fabrication of Double-Focused Ultrasound Transducers to Achieve Tight Focusing

Jang

Chang

2016

Sensors

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Beauty treatment for skin requires a high-intensity focused ultrasound (HIFU) transducer to generate coagulative necrosis in a small focal volume (e.g., 1 mm3) placed at a shallow depth (3–4.5 mm from the skin surface). For this, it is desirable to make the F-number as small as possible under the largest possible aperture in order to generate ultrasound energy high enough to induce tissue coagulation in such a small focal volume. However, satisfying both conditions at the same time is demanding. To meet the requirements, this paper, therefore, proposes a double-focusing technique, in which the aperture of an ultrasound transducer is spherically shaped for initial focusing and an acoustic lens is used to finally focus ultrasound on a target depth of treatment; it is possible to achieve the F-number of unity or less while keeping the aperture of a transducer as large as possible. In accordance with the proposed method, we designed and fabricated a 7-MHz double-focused ultrasound transducer. The experimental results demonstrated that the fabricated double-focused transducer had a focal length of 10.2 mm reduced from an initial focal length of 15.2 mm and, thus, the F-number changed from 1.52 to 1.02. Based on the results, we concluded that the proposed double-focusing method is suitable to decrease F-number while maintaining a large aperture size.

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Backscattering measurement from a single microdroplet

Cited by 8 publications

References 27 publications

Label-free analysis of the characteristics of a single cell trapped by acoustic tweezers

Label-free analysis of the characteristics of a single cell trapped by acoustic tweezers

Ultrasonic scattering measurements of a live single cell at 86 MHz

Design and Fabrication of Double-Focused Ultrasound Transducers to Achieve Tight Focusing

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