Gap Feedback Linearization of CMUTs for Harmonic Imaging and HIFU

用于谐波成像和 HIFU 的 CMUT 间隙反馈线性化

• 批准号: 8656105
• 负责人: F. Levent Degertekin
• 金额: $ 21.44万
• 依托单位: GEORGIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8656105
• 关键词: Amplifiers; Cardiology; Catheters; Charge; Clinical; Complex; Contrast Media; Dependence; Deposition; Detection; Devices; Diagnosis; Disease; Electrodes; Electronics; Electrostatics; Elements; Feedback; Foundations; Frequencies; Future; Generations; Heart Diseases; Image; Imaging Techniques; Indium; Investigation; Journals; Lead; Letters; Location; Malignant Neoplasms; Measurement; Measures; Membrane; Methods; Modeling; Motion; Output; Patients; Pattern; Performance; Phase; Physiologic pulse; Process; Publications; Research; Research Project Grants; Resolution; Scheme; Series; Signal Transduction; Source; System; Techniques; Technology; Therapeutic; Tissue Microarray; Tissues; Transducers; Translating; Ultrasonic Therapy; Ultrasonic Transducer; Ultrasonography; Work; attenuation; base; cold temperature; design; electric impedance; imaging modality; improved; novel; novel strategies; operation; pressure; public health relevance; simulation; stem; transmission process; tumor; voltage

DESCRIPTION (provided by applicant): A linear ultrasonic transducer with broad bandwidth and high output pressure capability would be ideal for improved tissue harmonic imaging (THI) and high intensity ultrasound applications which are proven to be useful for diagnosis and treatment of many diseases in clinical settings. Although CMUTs are shown to have broad bandwidth and being able to generate intensity levels suitable for therapeutic ultrasound, their inherently nonlinear transduction mechanism has been a significant barrier for these clinically important applications. While investigating the sources of nonlinearity in CMUTs, we recently developed a robust and practical method which overcomes this important bottleneck. The nonlinearity of the CMUT stems from the fact that the instantaneous force on the CMUT membrane is proportional to the square of the (V/g) ratio, where V is voltage on the transducer and g is the instantaneous membrane-substrate gap. By exciting the CMUT with an AC-only electrical signal at half the frequency of the desired pressure output, we cancel the voltage square nonlinearity. We then force the voltage on the CMUT to be inversely proportional to the instantaneous gap, and this cancels the 1/g dependence leading to significant reduction in harmonic generation. We achieve this by placing a judiciously chosen impedance element in series with the CMUT, or alternatively drive the CMUT using a current drive circuit. In contrast with earlier approaches for CMUT nonlinearity reduction, this method does not rely on complex pre-distorted waveforms. When CMUTs are linearized through gap feedback, membrane collapse can be avoided and the full device gap can be used for actuation. Therefore maximum pressure available from CMUT in non-collapse mode is obtained without DC charging problems. In the meantime, the inherent broad bandwidth of the CMUT for receive mode operation is retained, which is important for conventional and harmonic imaging. We obtained initial experimental results with different gap feedback topologies on single element CMUTs operating in the 1-10MHz range to demonstrate the method. The simulations indicate that harmonics can be reduced 40dB below fundamental, suitable for THI imaging. Based on these exciting results, in this project, we will explore this novel approach on CMUT arrays for THI, HIFU and dual-mode imaging-therapy applications. We will extend our model to include phased array operation and dual-electrode CMUTs to determine optimal array element and feedback topology for different applications. We will fabricate the CMUT arrays and evaluate gap feedback method through hydrophone measurements and compare with commercial piezoelectric arrays. We will quantitatively evaluate harmonic imaging performance of CMUT arrays using a commercial research ultrasound system on tissue mimicking commercial phantoms and contrast agents and compare with piezoelectric counterparts. We expect this study to be an important step in improving harmonic imaging and HIFU techniques in clinical settings by exploiting the full potential of the CMUT technology.

描述（由申请人提供）：具有广泛带宽和高输出压力能力的线性超声传感器非常适合改善组织谐波成像（THI）和高强度超声应用，该应用被证明可用于诊断和治疗许多临床疾病的诊断和治疗设置。尽管CMUT被证明具有宽阔的带宽，并且能够产生适合治疗性超声的强度水平，但是它们固有的非线性转导机制对于这些临床上重要的应用一直是一个重要的障碍。在研究CMUTS中非线性的来源时，我们最近开发了一种坚固且实用的方法，可以克服这种重要的瓶颈。 CMUT的非线性源于以下事实：CMUT膜上的瞬时力与（v/g）比的平方成正比，其中v在传感器上的V是电压，g是瞬时膜膜间隙。通过使用所需压力输出频率的一半的一半频率，通过使用AC的电信号激发CMUT，我们取消了电压平方非线性。然后，我们强迫CMUT上的电压与瞬时间隙成反比，这取消了1/g的依赖性，从而导致谐波产生显着降低。我们通过将明智选择的阻抗元件与CMUT串联放置，或者使用当前驱动电路驱动CMUT来实现这一目标。与较早的非线性降低方法相反，该方法不依赖复杂的预截止性波形。当CMUT通过间隙反馈线性化时，可以避免膜塌陷，并且可以将完整的设备缝隙用于致动。因此，在没有直流充电问题的情况下，获得了CMUT可从CMUT提供的最大压力。同时，保留了接收模式操作的CMUT固有的宽带宽度，这对于常规和谐波成像很重要。我们获得了在1-10MHz范围内运行的单个元素CMUT的不同差距反馈拓扑的初始实验结果，以证明该方法。模拟表明，可以将谐波降低到基本低于基本的40dB，适合于该成像。基于这些令人兴奋的结果，在这个项目中，我们将探讨这种有关THI，HIFU和双模式成像治疗应用的新型方法。我们将扩展模型以包括分阶段数组操作和双电极CMUTS，以确定不同应用程序的最佳数组元素和反馈拓扑。我们将制造CMUT阵列，并通过水文测量评估间隙反馈方法，并与商业压电阵列进行比较。我们将使用商业研究超声系统在模仿商业幻影和对比剂的组织上进行定量评估CMUT阵列的谐波成像性能，并与压电相对物进行比较。我们希望这项研究是通过利用CMUT技术的全部潜力来改善临床环境中谐波成像和HIFU技术的重要一步。

项目成果

Supply-Doubled Pulse-Shaping High Voltage Pulser for CMUT Arrays.

• DOI: 10.1109/tcsii.2017.2691676
• 发表时间: 2018-03
• 期刊: IEEE transactions on circuits and systems. II, Express briefs : a publication of the IEEE Circuits and Systems Society
• 作者: Jung G;Tekes C;Pirouz A;Degertekin FL;Ghovanloo M
• 通讯作者: Ghovanloo M

A nonlinear lumped model for ultrasound systems using CMUT arrays.

• DOI: 10.1109/tuffc.2015.007145
• 发表时间: 2015-10
• 期刊: IEEE transactions on ultrasonics, ferroelectrics, and frequency control
• 作者: Satir S;Degertekin FL
• 通讯作者: Degertekin FL

Phase and Amplitude Modulation Methods for Nonlinear Ultrasound Imaging With CMUTs.

使用 CMUT 进行非线性超声成像的相位和幅度调制方法。

• DOI: 10.1109/tuffc.2016.2557621
• 发表时间: 2016
• 期刊: IEEE transactions on ultrasonics, ferroelectrics, and frequency control
• 作者: Satir,Sarp;Degertekin,FLevent
• 通讯作者: Degertekin,FLevent