Directivity of photoacoustically generated ultrasound from a thin tube embedded in the soft phantom

Abstract

Authors’ previous study has revealed that the acoustic resonances had non-negligible effects on the photoacoustic signal for liquid sample confined in a thin tube. This paper presents numerical and experimental studies on the effects of tube’s hardness on the directivity of the generated photoacoustic signal. Thin glass capillary and silicone tube of 1 mm in diameter were tested with a pulsed light of 637 nm in wavelength. Black ink was confined in the capillary and tube as photoacoustic sample material. In the glass capillary, acoustic resonance modes in the tube was efficiently excited, and clear directivity was observed in the photoacoustic signals. On the other hand, little resonance was stimulated in the silicon tube because of the acoustic impedance matching between the sample and surrounding media, which resulted in weak confinement of acoustic waves. The results suggested a possibility of characterization of the physical properties of thin tube.

Estimation of the composition ratio of two contents filled in an elastic thin tube through laser-diode-based photoacoustic measurements

“…Being based on the resonance conditions inside the tube analyzed in Ref. 38, the optimum pulse width is calculated to 290 ns. The discrepancy between the theory and the peak position in Fig.…”

“…37) Directivity characteristics of the PA signals from a glass capillary and a soft silicone tube embedded in a soft phantom using black ink as the target liquid were investigated. 38) The influence of the acoustic modes in the tubes and the elastic properties of the tube wall on the frequency response and directivity of the PA signal were clarified.…”

Electromagnetically spinning viscometer designed for measurement of low viscosity in low shear rate region

“…In addition, knowledge on the rheology of blood and soft tissues is important for bio-ultrasonic investigations. [5][6][7][8][9][10][11] Besides the bio and medical fields, low viscosity liquids are promising material in advanced micro fluid technologies such as inkjet and micro-fluidics. [12][13][14][15][16][17][18][19] In this paper, we propose a new application of an EMS viscosity measurement system to extend the measurement range to a lower shear rate for low-viscosity samples.…”

Optimization design of the coupling scheme of the pulse laser output through the hysteroscope observation channel

“…Therefore, to better diagnose and treat endometrial cancer [8][9] , it must be diagnosed and treated promptly at an early stage or before malignant lesions are present. In the early detection of endometrial cancer tumor tissue, photoacoustic imaging [10][11] can be used in combination with hysteroscopy [3] , which mainly involves laser [12][13] coupling to the light source end of the hysteroscope and entering the uterine cavity through the hysteroscopic viewing channel to excite the tumor tissue in the uterine cavity to produce ultrasound, thus detecting an ultrasound signal different from that of normal tissue and thus making a diagnosis. After literature research, no application of pulsed laser coupling [14][15] through the hysteroscopic viewing channel for early endometrial cancer detection has been found.…”