Optoacoustic Transducer Based On Carbon Nanotube-polydimethylsiloxane Composites

With the advantages of safety,convenience,low cost,and good real-time,ultrasound technology has always been favored and play an important role in clinical diagnosis and treatment.As is known,transducer is indispensable for ultrasound technology.So far,the piezoelectric ultrasound transducer,which is driven by electricity,has been the main stream used in medicine.It produces and receives the ultrasound by virtue of the piezoelectric and converse piezoelectric effect,respectively.However,as an active device,such transducer has a high driving voltage and the electrical contacts limit its miniaturization.The optoacoustic transducer has also been researched intensely,which produces the ultrasound by the pulsed laser based on the optoacoustic materials.The optoacoustic material is composed of the inorganic and organic material.The inorganic material absorbing the light,transform the optical energy into the heat energy.Then the ultrasound will be generated due to the expansion of the organic material after it absorbs the heat energy.Due to the material structure,the optoacoustic transducer has characteristics of small volume,wide frequency band and no crosstalk between adjacent elements,facilitating the miniaturization and integration relative to the piezoelectric transducer.Whereas,the low energy conversion efficiency is still a challenge for the optoacoustic transducer.In our work,the optoacoustic transducer with high conversion efficiency has been researched,which was realized through changing the material structure.The gold particles?AuNP?were added into the CNT yarn-PDMS composites,forming the CNT yarn-AuNP-PDMS ultrasound transducer.The high optoacoustic conversion efficiency originates from the increase of light absorption by the gold nanoparticle local plasmon resonance effect?LSPR?and efficient acoustic output through using PDMS as a flexible substrate.The prepared transducer was tested by a hydrophone under the action of a laser pulse.The peak sound pressure was 33.6MPa,and the energy conversion efficiency reached2.74×10^-2.Based on the thermoacoustic coupling theory,a simulation model was estabilshed,and the sound pressure values obtained through simulation were basically consistent with the experimental results.In addition,based on the photoemission process,the microscopic mechanism of the enhanced light absorption effect can be explained by the temperature changes at the interface of gold nanoparticles through COMSOL software.Finally,the manipulation of the 50?m particles was achieved utilizing the obtained optoacoustic transducer,offering the foundation for the application of such transducers in drug delivery.