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In this paper, we report new photoacoustic sensing (PAS) probe design based on silicon acoustic delay lines (SADLs). It consists of an optical fiber for light delivery and two SADLs for detecting/relaying the generated PA signals to an outside receiving transducer. Ultrasound testing shows that acoustic signals can be transmitted along the SADLs with low loss up to 17~20 MHz. To improve the PA excitation efficiency, a beveled tip is formed at the distal end of the optical fiber to align the optical illumination region with the acoustic detection zone of the SADLs. New polymer micro linkers fabricated with high-resolution 3-D printing are used to maintain the mechanical stability and acoustic isolation within the probe assembly. For demonstration, a prototype SADL-PAS probe was designed and fabricated. Its PA sensing performance (e.g., sensitivity, linearity, and depth resolution) is characterized. Testing results show that the SADL-PAS probe provides superior sensitivity with considerable high-frequency improvement. Ex-vivo tests in the chicken breast are conducted to demonstrate the PA target detection in biological tissues.

In this paper, we report a new photoacoustics (PA) sensing probe design using a single optical fiber for both light delivery and ultrasonic detection. This is made possible by the development and use of an optically transparent ultrasound transducer, which allows the excitation light to pass through and travel along the optical fiber to reach the target. In return, the transducer senses the generated PA signal transmitted through the optical fiber as an acoustic delay line. Optical transmission testing was performed to determine the transparency of the PMN-PT transducer. For demonstration, a prototype probe was designed, fabricated, and tested with black tape and red dye solutions as the target. The detection of an embedded target in the chicken breast was also demonstrated.

In this paper, we report a new photoacoustic sensing probe design consisting of two optical fibers. One optical fiber is used for delivering the excitation light pulses. The other one serves as an acoustic delay line to relay the generated PA signal from the target to an outside ultrasound transducer. With the addition of suitable time delay, the original PA signal can be easily separated from the interference signals. To demonstrate this new design, a prototype probe was designed, fabricated and tested. The PA sensing performance was characterized with different concentration of black and red dye solutions. The testing results show that the PA sensing probe can provide good sensitivity and maintain high linearity over a wide range of concentrations. The detection of bovine blood embedded into chicken breast tissue was also conducted to demonstrate its potential usefulness for in-vivo applications. Keywords: Photoacoustic sensing, Medical probe design, Optical fiber, Acoustic delay line

In this paper, we report a high-frequency photoacoustic sensing (PAS) probe design consisting of an optical fiber for light delivery and two silicon acoustic delay lines (SADLs) for detecting/relaying the PA signals. A beveled tip is formed at the distal end of the optical fiber to overlap the illumination region with the detection zone of the SADLs. Detected PA signals are transmitted through the SADLs with low loss at frequencies up to 17 MHz. For demonstration, a prototype PAS probe using SADLs is designed, fabricated, and tested. Testing results show that the PAS probe provides superior sensitivity with considerable high-frequency improvement.

In this paper, a novel photoacoustic (PA) sensing probe design consisting of single optical fiber is reported. The same optical fiber is used for light delivery, which also serves as an acoustic delay line to relay the PA signal. As the key feature of the design, the ultrasound transducer is made optically-transparent to allow excitation light to pass through. This probe design provides three major benefits, including miniaturization, co-registered optical excitation and acoustic detection, and clear separation of PA signal from interference signals. Testing results show that PA probe provides good sensitivity and high linearity.

In this paper, we report a new photoacoustic sensing probe design consisting of two optical fibers. One optical fiber is used for delivering the excitation light pulses. The other one serves as an acoustic delay line to relay the generated PA signal from the target to an outside ultrasound transducer. With the addition of suitable time delay, the original PA signal can be easily separated from the interference signals. To demonstrate this new design, a prototype probe was designed, fabricated and tested. The PA sensing performance was characterized with different concentration of black dye solutions. The testing results show that the PA sensing probe can provide good sensitivity and can maintain high linearity over a wide range of concentrations.

This paper reports the development of a new charge amplification approach for photoacoustic tomography (PAT) based on parallel acoustic delay line (PADL) arrays. By using a PADL array to create different time delays, multiple-channel PA signals can be received simultaneously with a single-element transducer followed by single-channel DAQ electronics for image reconstruction. Unlike the conventional voltage amplifiers whose output voltage drops with increasing transducer capacitance, both theoretical analysis and experimental results have shown that the charge amplification can provide almost constant transducer-amplifier gain, which is not affected by the transducer capacitance. Therefore, it allows the use of a large single-element transducer to interface many PADLs without sacrificing the SNR of each channel. This opens the possibility of using large PADL arrays to achieve PAT with a wide field of view and high lateral resolution.