Film-like Acoustic Microresonators for Wireless Monitoring of Intracardiac Pressure using Ultrasound

摘要 而使用植入物无线监测心内压对于心脏管理是必不可少的 失败，这些植入物的小型化是减少相关并发症的关键。目前植入物主要是 由电磁天线、电子设备以及能量存储和转换单元组成。然而，这些 单元含有有毒物质，需要一个大天线来传输大波长(&gt；5厘米)的 电磁波。目前植入物的大小和无机成分增加了 患者的并发症。 超声波技术有望取代电磁波用于体内无线通信。它是 安全，不干扰其他电磁信号，体内信号衰减较低，允许 由于其亚毫米波长，使用了小得多的天线和植入物。因此， 通过超声波进行通讯是微创压力监测植入物的理想选择。长的- 学期目标是开发一种基于超声波的无线技术，使心脏内植入物微型化。 通过取消电磁天线和能量存储和转换单元。的目标是 该项目是利用柔性，声学微谐振器(100至500微米厚的薄膜)与可压缩 用于测量心房和脑室生理压力的微腔。 我们的中心假设是来自谐振器及其共振器的回波信号的后处理 频率可以检测到心内压的变化。我们的理论基础是，由 聚二甲基硅氧烷(PDMS)形成声学谐振器。在PDMS中加入气体/空洞填充的微腔 胶片创造了一个谐振器，它对内外之间的压力差很敏感。正在改变 差压会导致谐振器变形。这些变形改变了电影的共鸣 允许检测压力变化的频率。 我们的具体目标是：1)证明水下谐振器在心脏和心脏的测量灵敏度 心房生理压力分辨率为~1毫米汞柱，时间分辨率为40毫秒；2)显示 通过加入血液相容材料，测试装置的体外安全性 耐久性，以及在特殊设计的体模中进行的测试；以及3)证明该植入物适合于最小限度的 在台式测试装置上进行侵入性分娩(跨中隔手术)。在项目完成后，该技术可以 立即被用来创造更安全的下一代体内压力监测植入物 使用声波。这一贡献意义重大，因为它可以帮助600多万与 心力衰竭(HF)，导致长期住院，花费160亿美元。建议的研究具有创新性。 因为这项技术只使用声波；避免了能量转换、存储单元和 电磁天线；并显著减少植入物的尺寸和并发症。

Abstract While wireless monitoring of intracardiac pressure using implants is essential for the management of heart failure, miniaturizing these implants is critical for reducing their associated complications. Current implants mainly consist of an electromagnetic antenna, electronics, and energy-storage and conversion units. However, these units contain toxic materials, and a large antenna is necessary to transmit the large wavelengths (>5 cm) of electromagnetic waves. The size and inorganic components of the current implants increase the risk of complications for patients. Ultrasound technology is promising to replace electromagnetic waves for in vivo wireless communications. It is safe, does not interfere with other electromagnetic signals, has lower in vivo signal attenuation, and permits the use of significantly smaller antennas and implants due to its sub-millimeter wavelength. Therefore, communication through ultrasound is ideal for use in minimally invasive pressure monitoring implants. The long- term objective is to develop an ultrasound-based, wireless technology that will miniaturize intracardiac implants by eliminating both the electromagnetic antenna and the energy storage and conversion units. The objective of this project is to utilize flexible, acoustic microresonators (100 to 500 µm thick films) with compressible microcavities for physiological pressure measurements of atriums and ventricles. Our central hypothesis is that the post-processing of echo signals from the resonators and their resonant frequencies can detect intracardiac pressure changes. Our rationale is that micro-fabricated films made from polydimethylsiloxane (PDMS) form acoustic resonators. Incorporating gas/void filled microcavities into the PDMS film creates a resonator that is sensitive to the pressure difference between the inside and outside. Changing the differential pressure causes deformations of the resonator. These deformations shift the film's resonant frequency allowing for the detection of pressure changes. Our specific aims are to 1) prove the measurement sensitivity of the resonator underwater at the ventricular and atrial physiological pressures with the resolution of ~1mmHg and temporal resolution of 40 (ms); 2) demonstrate the safety of an implantable device in vitro by incorporating hemocompatible materials, testing a device's durability, and testing in a specially designed phantom; and 3) prove that the implant is suitable for a minimally invasive delivery (transseptal procedure) on a benchtop test setup. Upon project completion, the technology can be immediately employed to create safer next-generation in vivo pressure monitoring implants that operate solely using acoustic waves. This contribution is significant because it can aid over 6 million Americans who live with Heart Failure (HF), resulting in chronic hospitalizations that cost $16 billion. The proposed research is innovative because this technology employs only acoustic waves; avoids energy conversion, storage units, and electromagnetic antennas; and significantly reduces an implant's size and complications.