Ahmed Benozir, Reiche Christopher F, Magda Jules J, Solzbacher Florian, Körner Julia
Department of Electrical & Computer Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
Department of Chemical Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
ACS Appl Polym Mater. 2024 Apr 23;6(9):5544-5554. doi: 10.1021/acsapm.4c00808. eCollection 2024 May 10.
Stimulus-responsive (smart) hydrogels are a promising sensing material for biomedical contexts due to their reversible swelling change in response to target analytes. The design of application-specific sensors that utilize this behavior requires the development of suitable transduction concepts. The presented study investigates a power-transfer-based readout approach that is sensitive to small volumetric changes of the smart hydrogel. The concept employs two thin film polyimide substrates with embedded conductive strip lines, which are shielded from each other except at the tip region, where the smart hydrogel is sandwiched in between. The hydrogel's volume change in response to a target analyte alters the distance and orientation of the thin films, affecting the amount of transferred power between the two transducer parts and, consequently, the measured sensor output voltage. With proper calibration, the output signal can be used to determine the swelling change of the hydrogel and, consequently, to quantify the stimulus. In proof-of-principle experiments with glucose- and pH-sensitive smart hydrogels, high sensitivity to small analyte concentration changes was found along with very good reproducibility and stability. The concept was tested with two exemplary hydrogels, but the transduction principle in general is independent of the specific hydrogel material, as long as it exhibits a stimulus-dependent volume change. The application vision of the presented research is to integrate in situ blood analyte monitoring capabilities into standard (micro)catheters. The developed sensor is designed to fit into a catheter without obstructing its normal use and, therefore, offers great potential for providing a universally applicable transducer platform for smart catheter-based sensing.
刺激响应型（智能）水凝胶因其对目标分析物的可逆溶胀变化，在生物医学领域是一种很有前景的传感材料。利用这种特性设计特定应用的传感器需要开发合适的传感转换概念。本研究探讨了一种基于功率传输的读出方法，该方法对智能水凝胶的微小体积变化敏感。该概念采用两个带有嵌入式导电带状线的聚酰亚胺薄膜基板，除了在尖端区域外，它们相互屏蔽，智能水凝胶夹在尖端区域之间。水凝胶对目标分析物的体积变化改变了薄膜之间的距离和方向，影响了两个传感转换部件之间的功率传输量，从而影响测量的传感器输出电压。经过适当校准，输出信号可用于确定水凝胶的溶胀变化，进而量化刺激。在对葡萄糖和pH敏感的智能水凝胶的原理验证实验中，发现对分析物浓度的微小变化具有高灵敏度，同时具有非常好的重现性和稳定性。该概念用两种示例性水凝胶进行了测试，但一般来说，传感转换原理与特定的水凝胶材料无关，只要它表现出与刺激相关的体积变化即可。本研究的应用愿景是将原位血液分析物监测功能集成到标准（微）导管中。所开发的传感器设计成可适配到导管中而不妨碍其正常使用，因此，为基于智能导管传感提供通用适用的传感转换平台具有巨大潜力。
