Ultrasensitive microresonator based on molecular imprinted hydrogels

该项目的主要目标是实现一种具有集成分子印迹水凝胶的概念性新型低损耗剪切微谐振器，以实现对液相中化学或生物化合物的超灵敏特异性识别。该项目的愿景是开发化学选择性微传感器，用于快速可靠的分析（例如兴奋剂检测，临床分析）。液体流动池环境将提供稳定的操作和可重复使用性，这种高度跨学科的研究活动提供了物理学家和化学工程师的密切合作，将1）低损耗微谐振器的科学领域融合在一起，（品质因数高于100）在粘性流体中具有高灵敏度，以及2）分子印迹水凝胶薄膜对各种化合物具有巨大的选择性。化学选择性依赖于在合成过程中与分析物的分子印迹过程。从液体中选择性地吸收分析物增加了微谐振器的总质量/惯性。这导致谐振频率的降低，这是可访问的高精度实现部分浸没的专利概念的微谐振器在液体接触。在流体操作过程中的品质因数的改善，从而实现进一步降低的质量检测限最近在该项目中证明了引入一种新的适应剪切桥微谐振器。集成的响应凝胶层的重要成就是一个合适的干法蚀刻工艺的发展，以及改善的粘附到下面的微谐振器表面。总之，在第一个项目期间成功地实现了将两个科学专门知识领域联合收割机结合起来的关键要求。在第三个研究年度，将通过在水凝胶形成过程中使用分析物的分子印迹过程来实现化学选择性谐振器。这产生了具有适当分子间性质（氢键等）的结构特定的3D空腔，类似于锁和钥匙原理。这需要调整我们开发的合成方案，并且还允许分析物的反冲洗和凝胶的重复使用（通过pH值或温度可调节的膨胀-收缩）。我们将专注于一个著名的模型系统，从以前的作品，两个黄嘌呤衍生物，咖啡因和头孢唑啉（茶碱）。通过该模型系统，将确定感官特性的极限，如选择性、灵敏度、交叉选择性和时间行为。为了保证再现性并保持部分润湿，微谐振器将被集成并在优化的流体单元环境中操作。

The main goal of the project is to implement a conceptual new, low-loss shearing microresonator with an integrated molecular imprinted hydrogel to enable ultrasensitive specific recognition of chemical or biological compounds from liquid phases. The vision of the project is the development of chemical selective microsensors for fast and reliable analytics (e.g. doping tests, clinical analysis). A liquid flow cell environment will provide stable operation and reusability, which has also a positive cost impact.This highly interdisciplinary research activity affords the close collaboration of physicist and chemical engineers merging the scientific fields of 1) low-loss microresonators (quality factor higher than 100) in viscous fluids with high sensitivity and 2) thin films of molecular imprinted hydrogels with their enormous selectivity to a variety of chemical compounds. Chemical selectivity relies on the molecular imprinting process with an analyte during synthesis. The selective uptake of an analyte from a liquid increases the overall mass/inertia of the microresonator. This causes the reduction of the resonant frequency which is accessible with high accuracy implementing the patented concept of partial immersion for microresonators in liquid contact. The improvement of the quality factor during fluid operation and thus the achieved further reduction of the mass detection limit were recently demonstrated in this project introducing a novel adapted shearing bridge microresonator. The important achievements for the integration of the responsive gel layers were the development of a suitable dry etching process as well as the improvement of the adhesion to the underlying microresonator surface. In summary, the key requirements to combine both scientific areas of expertise were successfully implemented in the first project period. In the third research year a chemoselective resonator will be implemented via a molecular imprinting process using the analyte during hydrogel formation. This creates structural specific 3D cavities with appropriate intermolecular properties (hydrogen bounds, etc.), similar to a lock-and-key principle. This needs an adjustment of our developed synthesis protocols and also allows a backwash of the analyte and reuse of the gel (swelling-shrinking via pH or temperature adjustable). We will focus on a well-known model system from previous works, two xanthine derivatives, caffeine and cefazoline (theophylline). With this model system the limits of sensory properties, like selectivity, sensitivity, cross selectivity, and time behavior will be determined. To guarantee reproducibility and maintain partial wetting, the microresonator will be integrated and operated into an optimized fluid cell environment.