Silveira Fiates Ana Luiza, Almeida Renato S M, Wilhelm Michaela, Rezwan Kurosch, Vellekoop Michael J
Institute for Microsensors, -Actuators and -Systems (IMSAS), University of Bremen, Bremen 28359, Germany.
Microsystems Center Bremen (MCB), 28359Bremen, Germany.
ACS Omega. 2024 Sep 23;9(40):41480-41490. doi: 10.1021/acsomega.4c05019. eCollection 2024 Oct 8.
Silica aerogels are highly porous materials with unique properties such as high specific surface area, high thermal insulation, and high open porosity. These characteristics make them attractive for several applications in closed microfluidic channels such as BioMEMS, catalysis, and thermal insulation. However, aerogel-filled microchannels have not been reported in the literature yet because of the complexity of creating a process that controls the integration, shrinkage, and mechanical stability of these materials inside a closed channel. In this work, a process is presented to integrate aerogels in microchannels with reproducibility, mechanical stability, and no shrinkage. This protocol is based on the filling of channels during the gelation, which is crucial to avoid shrinkage, CO supercritical drying, and mechanical additives (polyethylene glycol and carbon nanotubes). Furthermore, the influence of polyethylene glycol and carbon nanotubes on the compressive strength, porosity, and specific surface area is investigated. Following the suggested process protocol, the integration of different aerogel compositions (with and without reinforcement) is successfully achieved in the microchannels without shrinkage and cracks. This research opens up new possibilities for the use of different aerogels in microfluidics with structural integrity and enhanced functionality.
二氧化硅气凝胶是具有高比表面积、高隔热性和高开孔率等独特性能的高度多孔材料。这些特性使其在诸如生物微机电系统、催化和隔热等封闭微流控通道的多种应用中具有吸引力。然而，由于在封闭通道内创建一个控制这些材料的集成、收缩和机械稳定性的过程较为复杂，气凝胶填充的微通道在文献中尚未见报道。在这项工作中，提出了一种在微通道中集成气凝胶的方法，该方法具有可重复性、机械稳定性且无收缩。该方案基于在凝胶化过程中填充通道，这对于避免收缩、二氧化碳超临界干燥以及机械添加剂（聚乙二醇和碳纳米管）至关重要。此外，还研究了聚乙二醇和碳纳米管对抗压强度、孔隙率和比表面积的影响。按照建议的工艺方案，在微通道中成功实现了不同气凝胶组合物（有增强和无增强）的集成，且无收缩和裂缝。这项研究为在微流控中使用具有结构完整性和增强功能的不同气凝胶开辟了新的可能性。
