罗谢尔盐是已报道的压电、铁电材料,具有较大的压电响应曾作为理想的机电超声换能器材料受到广泛的关注。然而，由于罗谢尔盐材料在潮湿环境中具有不稳定性，其在生物电子学方面潜在应用少有研究。本课题旨在探索单晶罗谢尔盐单晶薄膜材料的制备工艺和性能表征，评估其在生物电子器件中的应用潜力。基于系统的研究，获得了以下结论与成果： (1) 提出了独特的罗谢尔盐单晶生长工艺，实现了快速的单晶罗谢尔盐的生长 (10 毫米/天)。 通过引入简单的 “晶体抛光” 方法，沿所需晶面 (100) 实现了不同厚度 (500-190 ?m) 的罗谢尔盐单晶薄膜。 (2) 针对罗谢尔盐单晶材料在水性环境中易溶解的关键挑战，提出了可降解的左旋聚乳酸 (PLLA)和聚酸酐的复合封装材料，可维持罗谢尔盐晶体在水溶液中持续5天的稳定性 (37 oC)。 (3) 基于冲击和超声波方法对罗谢尔盐晶体薄膜进行压电测量，获得了块状晶体和薄膜的 g33 分别为 12 mV·m/N 和 37 mV·m/N 的压电性能。在超声波测试中，在 5 kPa 声压下，罗谢尔盐晶体薄膜的压电输出性能为 0.5 mV，约为传统压电材料 PVDF 的两倍。基于优异的压电输出性能，罗谢尔盐晶体材料有望应用于生物可降解电子器件。本研究可为开拓罗谢尔盐在生物电子器件领域的应用奠定重要的基础。罗谢尔盐具有较高的压电输出与优异的生物可降解特性，适用于生物传感器、制动器、能量收集器以及超声换能器等功能性器件。进一步优化罗谢尔盐单晶薄膜材料的制备工艺，探索其降解规律，并开发相应的可降解封装材料，有望最终实现基于罗谢尔盐的新型可降解电子器件。
Rochelle Salt is a well-known piezoelectric and ferroelectric material. It has a large piezoelectric response and has received widespread attention as an ideal electromechanical ultrasonic transducer material. However, due to the instability of Rochelle Salt crystal in humid environments, its potential applications in bioelectronics have been least studied. This work explores the preparation process, piezoelectric performance, and characterization of Rochelle Salt crystal and thin films and evaluates its application potential in bioelectronic devices. Based on systematic research, the following results and conclusions are obtained:(1) Herein we report a unique, unidirectional “Partial Exposure” strategy to grow Rochelle Salt crystal with the fastest crystal growth rate (10 mm/day) recorded. Furthermore, for the first time, we report the fabrication of Rochelle Salt Crystal-based thin films of variable thickness (500-190 μm) along the desired crystal plane (100) by introducing our simple “Crystal Polishing” approach. (2) The stability challenge was addressed using biodegradable polymers hybrid encapsulations of PLLA and Polyanhydride with reported 5 days of crystal stabilization in the water bath at 37 oC. (3) Additionally, piezoelectric measurements are reported using impact and ultrasonic methods for the bulk crystals and fabricated thin film with special emphasis along the (100) crystal plane. The reported g33 is 12 mV·m/N and 37 mV·m/N for the bulk crystal and thin film respectively. In ultrasonic testing, the voltage output of Rochelle Salt was compared with well-known piezoelectric PVDF at a sound pressure of 5 kPa, the generated voltage output for the Rochelle Salt is 0.5 mV, which is almost double as compared to 0.25 mV of PVDF, which is sufficiently high enough to revolutionize the bioelectronics era.Hence, this work sets the foundation and provides the possible solution to all the concerns limiting the practical applications of Rochelle Salt in the past few centuries for bioelectronics devices. As reported, the sufficiently high piezoelectric measurements could set biodegradable piezoelectric Rochelle Salt as a material of great interest among the researchers to present Rochelle Salt as a potential choice for biosensors, actuators, energy harvesters, and especially in the development of ultrasonic transducers. In the near future, significant attention is needed towards making a flexible device design for in-vivo applications based on single crystalline thin film micro-structured fragments followed by recording their functional and structural degradation behaviors. Although this work provides ideas and possible ways to stabilize the Rochelle Salt in water presence, in the future more attention is required for long-term stability and excellent device performance aim which requires strong device encapsulation materials. However, optimization is needed for each step, which may present a challenging task.
