Bonyár Attila, Nagy Ágoston G, Gunstheimer Hans, Fläschner Gotthold, Horvath Robert
Department of Electronics Technology, Faculty of Electrical Engineering and Informatics, Budapest University of Technology and Economics, Budapest, Hungary.
Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, Centre for Energy Research, HUN-REN, Budapest, Hungary.
Microsyst Nanoeng. 2024 Feb 18;10:26. doi: 10.1038/s41378-023-00629-6. eCollection 2024.
Fluidic force microscopy (FluidFM) fuses the force sensitivity of atomic force microscopy with the manipulation capabilities of microfluidics by using microfabricated cantilevers with embedded fluidic channels. This innovation initiated new research and development directions in biology, biophysics, and material science. To acquire reliable and reproducible data, the calibration of the force sensor is crucial. Importantly, the hollow FluidFM cantilevers contain a row of parallel pillars inside a rectangular beam. The precise spring constant calibration of the internally structured cantilever is far from trivial, and existing methods generally assume simplifications that are not applicable to these special types of cantilevers. In addition, the Sader method, which is currently implemented by the FluidFM community, relies on the precise measurement of the quality factor, which renders the calibration of the spring constant sensitive to noise. In this study, the hydrodynamic function of these special types of hollow cantilevers was experimentally determined with different instruments. Based on the hydrodynamic function, a novel spring constant calibration method was adapted, which relied only on the two resonance frequencies of the cantilever, measured in air and in a liquid. Based on these results, our proposed method can be successfully used for the reliable, noise-free calibration of hollow FluidFM cantilevers.
流体动力显微镜（FluidFM）通过使用带有嵌入式流体通道的微加工悬臂，将原子力显微镜的力灵敏度与微流体的操作能力融合在一起。这一创新开启了生物学、生物物理学和材料科学领域新的研发方向。为了获取可靠且可重复的数据，力传感器的校准至关重要。重要的是，中空的FluidFM悬臂在矩形梁内部包含一排平行支柱。对内部结构悬臂进行精确的弹簧常数校准绝非易事，并且现有方法通常采用的简化假设不适用于这些特殊类型的悬臂。此外，目前FluidFM领域所采用的萨德（Sader）方法依赖于品质因数的精确测量，这使得弹簧常数的校准对噪声敏感。在本研究中，使用不同仪器通过实验确定了这些特殊类型中空悬臂的流体动力学函数。基于流体动力学函数，采用了一种新颖的弹簧常数校准方法，该方法仅依赖于在空气中和液体中测量的悬臂的两个共振频率。基于这些结果，我们提出的方法能够成功用于对中空FluidFM悬臂进行可靠的、无噪声的校准。
