Significance: Photoacoustic imaging has shown advantages over the periodontal probing method in measuring the periodontal probing depth, but the large size of conventional photoacoustic transducers prevents imaging of the more posterior teeth.
Aim: Our aim is to develop a photoacoustic imaging system to image the more posterior periodontal pocket.
Approach: We report a clinical “hockey-stick”-style transducer integrated with fibers for periodontal photoacoustic imaging. Cuttlefish ink labeled the periodontal pocket as the photoacoustic contrast agent.
Results: We characterized the imaging system and then measured the pocket depth of 35 swine teeth. Three raters evaluated the performance of the hockey-stick transducer. The measurements between the Williams probing (gold standard) and the photoacoustic methods were blinded but highly correlated. We showed a bias of ∼0.3 mm for the imaging-based technique versus Williams probing. The minimum inter-reliability was over 0.60 for three different raters of varying experience, suggesting that this approach to measure the periodontal pocket is reproducible. Finally, we imaged three pre-molars of a human subject. We could access more upper and posterior teeth than conventional linear transducers.
Conclusions: The unique angle shape of the hockey-stick transducer allows it to image more posterior teeth than regular linear transducers. This study demonstrated the ability of a hockey-stick transducer to measure the periodontal pocket via photoacoustic imaging.
Distributed sensors have become a great advantage for Structural Health Monitoring (SHM) as they allow for the multiple points measurement using a single sensor. Nevertheless, the installation of this technology can be time-consuming and have an impact on the overall cost of the project. For this reason, this paper explores the application of different techniques for embedding fiber optic cable into textile for Distributed Optical Sensors which could greatly reduce the installation time. This embedding also provides the ability to design sensors with different patterns that enable monitoring structures like pipelines, bridges, and others. In this paper we have identified an embedding technique that does not damage the fiber optic cable. Additionally, the sensors were tested to study their response to temperature and strain by using Brillouin Optical Time Domain Amplification (BOTDA) interrogation technique.
This paper presents the design, fabrication, and characterization of a novel all-optical fiber ultrasound imaging system based on the photoacoustic (PA) ultrasound generation principle and Fabry-Perot interferometer principle for biomedical imaging applications. This system consists of a fiber optic ultrasound generator and a Fabry–Perot (FP) fiber sensor receiver. A carbon black polydimethylsiloxane (PDMS) material was utilized as the photoacoustic material for the fiber optic ultrasound generator. The black PDMS material was coated on the tip of a 1000 μm core size multimode fiber (MMF) to generate the ultrasound signal. Two layers of gold, PDMS and a single mode fiber (SMF) were used to build the FP fiber sensor receiver. The system verification test proves the ultrasound sensing capability. The biomedical imaging test validates the ultrasound imaging capability. There are many advantages of this all-optical fiber ultrasound imaging system, such as small size, light weight, ease of use, and immunity to electromagnetic interference. This research has revealed valuable knowledge for the further study of biomedical imaging in a limited space, e.g., catheter based intravascular imaging, tissue characterization, tissue identification and related biomedical applications.
In this paper, we present a novel fiber optic ultrasonic sensing system to conduct a 2D temperature field monitoring. The fiber optic ultrasonic sensing system was used as an ultrasonic pyrometer to measure the temperature field. The ultrasonic pyrometer was based on the thermal dependence of the speed of sound in air. The speed of a sound wave traveling in a medium was proportional to the medium’s temperature. A fiber optic ultrasonic generator and a microphone were used as the ultrasonic signal generator and receiver, respectively. A carbon blackPolydimethylsiloxane (PDMS) material was utilized as the photoacoustic material for the fiber optic ultrasonic generator. A test was performed outside of a lab furnace, the testing area temperature range was from 26°C to 70°C. A 2D temperature field was mapped. The 2D temperature field map matched with the reference thermocouple results. This system could lead to the development of a new generation temperature sensor for temperature field monitoring in coalfired boilers or exhaust gas temperature monitoring for turbine engines.
This paper presents a characterization of ultrasonic generation from the sidewall of an optical fiber. Ultrasonic generation from an optical fiber could have broad applications, such as ultrasonic imaging, ultrasonic nondestructive test (NDT), and acoustic pyrometers and so on. There are many advantages of these fiber-optic ultrasonic transducers, such as small size, light weight, ease of use, and immunity to electromagnetic interference. This paper discusses two main factors that will influence the signal strength generated by the sidewall of the ultrasonic generator. The two factors are the thickness of the photoabsorption material and the optical energy emitted from the sidewall fiber. A 20 mm length fiber-optic sidewall ultrasonic generator was used for the characterization. Gold-nanocomposite materials were used as the photoabsorption material. A hydrophone was used to detect the ultrasonic signal. The ultrasonic time and frequency profile and the ultrasonic field distribution at the longitudinal section of this fiber-optic sidewall ultrasonic generator have been characterized in this paper.
This paper presents a novel fiber optic ultrasonic sensing system to measure high temperature in the air. Traveling velocity of sound in a medium is proportional to medium’s temperature. The fiber optic ultrasonic sensing system was applied to measure the change of sound velocity. A fiber optic ultrasonic generator and a Fabry-Perot fiber sensor were used as the signal generator and receiver, respectively. A carbon black- Polydimethylsiloxane (PDMS) material was utilized as the photoacoustic material for the fiber optic ultrasonic generator. A water cooling system was applied to cool down the photoacoustic material. A test was performed at lab furnace environment (up to 700 ℃). The sensing system survived 700℃. It successfully detect the ultrasonic signal and got the temperature measurements. The test results agreed with the reference sensor data. The paper validated the high temperature measurement capability of the novel fiber optic ultrasonic sensing system. The fiber optic ultrasonic sensing system could have broad applications. One example is that it could serve as acoustic pyrometers for 3D temperature distribution reconstruction in an industrial combustion facility
Ultrasonic wave based structural health monitoring (SHM) is an innovative method for nondestructive detection and an
area of growing interest. This is due to high demands for wireless detection in the field of structural engineering. Through
optically exciting and detecting ultrasonic waves, electrical wire connections can be avoided, and non-contact SHM can
be achieved. With the combination of piezoelectric transducer (PZT) (which possesses high heat resistance) and the noncontact
detection, this system has a broad range of applications, even in extreme conditions. This paper reports an all-optically
driven SHM system. The resonant frequencies of the PZT transducers are sensitive to a variety of structural
damages. Experimental results have verified the feasibility of the all-optically driven SHM system.
Ultrasonic temperature measurements have been developed and widely applied in non-contact temperature tests in many industries. However, using optical fibers to build ultrasound generators are novel. This paper reports this new fiber optic ultrasonic system based on the generator of gold nanoparticles/polydimethylsiloxane (PDMS) composites. The optical acoustic system was designed to test the change of temperature on the aluminum plate and the temperature of the torch in the air. This paper explores the relationship between the ultrasonic transmission and the change of temperature. From the experimental results, the trend of ultrasonic speed was different in the aluminum plate and air with the change of temperature. Since the system can measure the average temperature of the transmission path, it will have significant influence on simulating the temperature distribution.
Ultrasound generation from an optical fiber, based on the photoacoustic principle, could have broad applications, such as
ultrasound nondestructive test (NDT) and biomedical ultrasound imaging. There are many advantages of these fiber-optic
ultrasonic transducers, such as small size, light weight, ease of use, and immunity to electromagnetic interference.
This paper will demonstrate a novel structure which the ultrasound signal is generated on the sidewall of the fiber. Two
experimental configurations of the fiber-optic sidewall ultrasonic transducer are discussed. One is that a photoacoustic
material is directly coated on the sidewall of the optical fiber. The other one is that the photoacoustic material is directly
coated on an aluminum plate and the sidewall fiber is buried in the material. By using this novel sidewall ultrasound
generator, we can effectively generate ultrasound signal at multiple, particular locations along one fiber.
Fiber optic acoustic generators have generated a lot of interest due to its great potential in many applications including nondestructive tests. This paper reports four acoustic generation configurations. All the configurations are based on gold nanoparticles/polydimethylsiloxane (PDMS) composites. Since gold nanoparticles have high absorption efficiency to optical energy and PDMS has a high coefficient of thermal expansion, the composites can transfer optical energy to ultrasonic waves with high conversion efficiency. The strength and bandwidth of ultrasonic waves generated by the composites can be changed by different designs and structures of the composites. This paper explores the relation between the structure of fiber optic acoustic generators and the profile of generated ultrasonic waves. Experimental results also demonstrated that four ultrasonic generation configurations have similar features of ultrasonic transmission on a steel plate, which is important for future choices of ultrasonic receivers.
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