Ultrasensitive microresonator based on molecular imprinted hydrogels

该项目的主要目标是实现一种概念性的新型低损耗剪切微谐振器，该谐振器带有集成的分子印迹水凝胶，可以对液相中的化学或生物化合物进行超灵敏的特异性识别。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（例如兴奋剂测试，临床分析）。液体流动电池环境将提供稳定的操作和可重复使用性，这也对成本产生积极影响。这项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，融合了高灵敏度粘性流体中的低损耗微谐振器（质量因子高于100）和对各种化合物具有巨大选择性的分子印迹水凝胶薄膜的科学领域。化学选择性依赖于合成过程中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。这导致共振频率的降低，这是实现微谐振器在液体接触中部分浸入的专利概念的高精度。最近，本项目介绍了一种新型的自适应剪切桥微谐振器，证明了流体运行过程中质量因子的改善，从而进一步降低了质量检测极限。响应凝胶层集成的重要成果是开发了合适的干蚀刻工艺以及改善了与底层微谐振器表面的粘附性。总之，在第一个项目期间成功地实现了将两个科学领域的专门知识结合起来的关键要求。在研究的第三年，化学选择性谐振器将通过分子印迹工艺在水凝胶形成过程中使用分析物来实现。这创建了具有适当分子间性质（氢键等）的结构特定的3D腔，类似于锁与钥匙原理。这需要对我们开发的合成方案进行调整，并允许分析物的反冲洗和凝胶的再利用（通过pH值或温度调节膨胀收缩）。我们将集中在一个众所周知的模型系统，从以前的工作，两个黄嘌呤衍生物，咖啡因和头孢唑啉（茶碱）。有了这个模型系统，感官特性的限制，如选择性、灵敏度、交叉选择性和时间行为将被确定。为了保证重现性和保持部分润湿，微谐振器将集成并运行在优化的流体电池环境中。

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.