植入式器件新型可控降解技术研究

Implantable and resolvable medical devices are of great significance in theory and very promising for widespread applications including vital sign monitoring, disease warning and drug delivery. The encapsulation with controlled degradation is the core structure of such devices associated with outstanding characteristics including good biocompatibility, controlled dissolution rate, and forming minimally invasive interfaces to dynamic, soft biological systems. The research on the encapsulation with controlled degradation is in an early state and the study on this topic is mainly restricted by challenges of the poor ability of controlling the dissolution rate as well as the uncertain mechanism of dissolution regulation. To solve the problems, we will propose HfO2/Si nanomembrane (NM) bilayers as a new type of biofluid barrier encapsulation. The mechanism of the HfO2 capping layer regulating the reduction of Si NM dissolution rate will be illuminated by investigating the kinetics and chemistry of hydrolysis of the proposed encapsulation structure in the biofluid surrounding. Meanwhile, the physical and electrical models will be constructed to demonstrate the effect of the doping concentration on the dissolution behavior of the Si nanomembrane. The catalyzing effect of ions in the biofluid will be discussed in detail on the hydrolysis of the Si nanomembrane by conducting accelerated lifetime tests and failure analysis. Furthermore, the mechanism of HfO2 capping layer suppressing the catalyzing dissolution will be clarified. This study can guide the optimized design of the bilayer encapsulation structure for enhancing the ability of controlled degradation and hence providing technical reserves for developing the next generation implantable and resolvable electronics with controlled lifetime.

植入式可溶解医疗器件可用于患者体征监测、疾病预警、药物供给，具有重要理论意义和广泛的应用前景。集高生物相容性、可控溶解速率以及与生物组织良好贴合性等诸多优点于一身的可控降解封装层是该类器件的核心结构。目前，植入式器件可控降解封装层技术的研究在国际上刚刚起步，主要存在封装层材料降解速率可控性差且溶解调控机制不明等问题。本项目提出基于超薄HfO2/硅纳米膜的新型体液阻挡双封装层结构，通过研究该结构在生物体液中水解反应的动力学过程，阐明HfO2覆盖层对降低硅纳米膜水解速率的调控机理，构建硅中掺杂浓度调节硅纳米膜水解行为的物理和电学模型，通过加速寿命和失效分析实验研究，探明体液中离子对硅纳米膜水解作用的催化效应及化学机理，并阐明HfO2覆盖层对抑制催化水解的作用机理。通过本项目的研究，可以指导具备可控降解能力的双封装层结构的具体设计，为研制下一代寿命可控的植入式可溶解电子器件提供技术储备。

植入式可溶解医疗器件可用于患者体征监测、疾病预警、药物供给，具有重要理论意义和广泛的应用前景。集高生物相容性、可控溶解速率以及与生物组织良好贴合性等诸多优点于一身的可控降解封装层是该类器件的核心结构。目前，植入式器件可控降解封装层技术的研究在国际上刚刚起步，主要存在封装层材料降解速率可控性差且溶解调控机制不明等问题。本项目提出基于超薄HfO2/硅纳米膜的新型体液阻挡双封装层结构，通过研究该结构在生物体液中水解反应的动力学过程，阐明HfO2覆盖层对降低硅纳米膜水解速率的调控机理，构建硅中掺杂浓度调节硅纳米膜水解行为的物理和电学模型，通过加速寿命和失效分析实验研究，探明体液中离子对硅纳米膜水解作用的催化效应及化学机理，并阐明HfO2覆盖层对抑制催化水解的作用机理。通过本项目的研究，深入探索了硅纳米膜及HfO2覆盖的硅纳米膜在不同生理溶液和温度条件下的降解动力学过程及化学反应机制；提出总厚度仅为300 nm的三层薄膜封装结构，相比于传统1 um厚的热氧化生长的SiO2封装层，厚度减少了70 %，然而所保护的薄膜晶体管器件阈值电压稳定性提升超过30 %，据此申请国际PCT专利1项；研制了基于高质量HfO2/硅纳米膜界面的高性能瞬态电子器件，开关比超过1E7，栅泄漏电流低于0.1 pA。项目的研究成果为设计和制备具有可控降解能力的多层封装结构提供重要理论和实践基础，为研制下一代寿命可控的植入式可溶解电子器件提供技术储备。