本文選題：超聲換能器 + 鈮酸鋰　； 參考：《鄭州大學(xué)》2014年碩士論文

【摘要】：在超聲診斷和治療中，由于超聲功率過(guò)大可能引起人體細(xì)胞破壞性形變的空化效應(yīng)，超聲診斷安全性逐漸成為醫(yī)用超聲的重要問(wèn)題。在我國(guó)，計(jì)量部門主要采用毫瓦級(jí)或者瓦級(jí)超聲功率計(jì)來(lái)檢測(cè)各種醫(yī)用超聲設(shè)備的輸出功率，而超聲功率計(jì)則需要通過(guò)上一級(jí)計(jì)量部門進(jìn)行定期檢定或校準(zhǔn)，可見(jiàn)，超聲量值傳遞的準(zhǔn)確性為超聲技術(shù)使用的可靠性提供了保障。 本文從壓電超聲換能器的工作原理出發(fā)，理論上分析了鈮酸鋰單晶材料的壓電機(jī)理，壓電振子的振動(dòng)模式和壓電方程，并由壓電方程推導(dǎo)出壓電換能器在厚度伸縮振動(dòng)模式下的機(jī)電等效電路；在壓電材料的選擇方面，研究了鈮酸鋰單晶不同切割方向的振動(dòng)特性和機(jī)電耦合系數(shù)，確定壓電晶片的最佳切型及振動(dòng)模式；在壓電振子的設(shè)計(jì)方面，合理設(shè)計(jì)振子厚度與直徑的尺寸比例，并用濺射法在壓電振子表面鍍上金層電極薄膜；在換能器的制作方面，從換能器整體裝配和電極焊接角度出發(fā)，設(shè)計(jì)了超聲換能器的外殼，有效地降低了裝配難度。本文嚴(yán)格遵循“毫瓦級(jí)超聲功率計(jì)檢定規(guī)程”的要求，研制了標(biāo)稱頻率為5MHz的標(biāo)準(zhǔn)超聲換能器。 鈮酸鋰壓電超聲換能器的性能測(cè)試主要包括兩部分，分別為聲場(chǎng)特性測(cè)試和超聲輸出功率的標(biāo)定。聲場(chǎng)特性測(cè)試原理為水聽(tīng)器法，本文設(shè)計(jì)了確定換能器工作頻率的實(shí)驗(yàn)，，并測(cè)試了其在工作頻率下的聲場(chǎng)空間分布特性。按照毫瓦級(jí)標(biāo)準(zhǔn)超聲源的標(biāo)定要求，在毫瓦級(jí)國(guó)家基準(zhǔn)裝置上，采用輻射力天平法測(cè)量所研制的超聲換能器的輸出功率，并對(duì)實(shí)驗(yàn)結(jié)果進(jìn)行了不確定度評(píng)定。實(shí)驗(yàn)結(jié)果表明，所研制的換能器滿足“毫瓦級(jí)標(biāo)準(zhǔn)超聲源”的要求，達(dá)到了預(yù)期設(shè)計(jì)指標(biāo)，一定程度上克服了標(biāo)準(zhǔn)石英晶體超聲換能器的缺點(diǎn)。
[Abstract]:In ultrasonic diagnosis and treatment, the supersonic power may cause the cavitation effect of the destructive deformation of human cells. The safety of ultrasonic diagnosis has gradually become an important problem of medical ultrasound. In our country, the Metrology Department mainly uses milliwatt grade or watt grade ultrasonic power meter to detect the output power of various medical ultrasonic equipment, and the ultrasonic work The rate meter needs to be regularly calibrated or calibrated through the upper level measurement department. It can be seen that the accuracy of the transmission of ultrasonic values provides a guarantee for the reliability of ultrasonic technology.
Based on the working principle of the piezoelectric ultrasonic transducer, the piezoelectric mechanism of the lithium niobate single crystal material, the vibration mode and the piezoelectric equation of the piezoelectric vibrator are analyzed theoretically, and the electromechanical equivalent circuit of the piezoelectric transducer under the thickness expansion vibration mode is derived from the piezoelectric equation. The optimum cutting and vibration modes of the piezoelectric wafers are determined by the vibration characteristics and the electromechanical coupling coefficient of the crystal. In the design of the piezoelectric vibrator, the size ratio of the thickness and diameter of the vibrator is rationally designed, and the gold layer electrode film is plated on the surface of the piezoelectric vibrator by sputtering; the transducer is made from the transducer as a whole. In the angle of assembly and electrode welding, the outer shell of the ultrasonic transducer is designed, which effectively reduces the difficulty of assembly. In this paper, a standard ultrasonic transducer with a nominal frequency of 5MHz is developed in strict compliance with the requirements of the "milliwatt ultrasonic power meter verification regulation".
The performance test of the piezoelectric ultrasonic transducer for lithium niobate mainly consists of two parts, which are the sound field characteristic test and the calibration of the ultrasonic output power respectively. The sound field characteristic test principle is the hydrophone method. This paper designs the experiment to determine the working frequency of the transducer, and tests the spatial distribution characteristics of the sound field at the working frequency. The calibration requirement of the ultrasonic source is to measure the output power of the ultrasonic transducer developed by the radiation force balance method on the milliwatt national benchmark device, and evaluate the uncertainty of the experimental results. The experimental results show that the developed transducer meets the requirements of the "milliwatt standard super sound source" and has reached the expected design index. It overcomes the shortcomings of the standard quartz crystal transducer.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TB552

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 林順英;衛(wèi)闌

本文編號(hào)：2065988