Topography and near-field image measurement of soft biological samples in liquid by using a tuning fork based bent optical-fiber sensor

Abstract

The fabrication of a tuning fork based bent optical-fiber sensor and its application for topography and near-field image measurement of soft biological samples in physiological solution are reported. By adopting the bent optical fiber and tuning fork feedback scheme, the possibility of signal interference with stray light is minimized, which is especially important for near-field applications. From the measured tuning fork amplitude and its calibration with the preamplifier output voltage, it was determined that the interaction force between the fiber tip and a soft sample in liquid needs to be controlled within approximately 10 nN level and that the image quality depends sensitively to the interaction force. The results of topography measurements of fixed COS-7 and MCF-7 cells in phosphate buffered saline and of the near-field imaging of red blood cell also in phosphate buffered saline with a resolution of about 100 nm are presented.

Analysis of mitochondrial mechanical dynamics using a confocal fluorescence microscope with a bent optical fibre

“…The etching speed is affected by the etchant's concentration and the ambient temperature. Typically, the etching speed is 3.8 μm min −1 at 25°C. Step (b): The etched fibre was bent by a melting method (Kwon et al ., ). The etched side of the fibre was fixed on a commercial puller (P‐2000, Sutter Instrument, Novato, California, USA) and irradiated by a CO 2 laser set in the puller.…”

“…Step (b): The etched fibre was bent by a melting method (Kwon et al, 2011). The etched side of the fibre was fixed on a commercial puller (P-2000, Sutter Instrument, Novato, California, USA) and irradiated by a CO 2 laser set in the puller.…”

True Tapping Mode Scanning Near-Field Optical Microscopy with Bent Glass Fiber Probes

“…At the same time, one should keep in mind that with decreasing of values of the length L and keeping the relatively long probe's free part h new resonance mode will come into play. We studied the most popular scheme of the bent fiber attached to the TF in nonresonant conditions (see Figure 5(a) , similar parameters of bending were used in [ 17 ]). Such a rush method of fiber bending and attaching to the TF can lead to the reduced tapping mode efficiency due to the mode excitation on the probe's free part (see Figure 5(b) ), whereas oscillations happen mostly in the Oy direction; the value of ψ for this mode is less than 0.05.…”

“…A few realizations of this approach were based on straight optical fibers or short fragments thereof correctly attached to the tuning fork or bimorph [ 15 , 16 ]. However, the use of natural long but bent optical fibers attached to the tuning fork in a standard fashion seems was the most popular [ 17 ]. However, the detailed analysis of the relative fiber-sample surface motion in these experiments has not been performed.…”

Nanocharacterization of Soft Biological Samples in Shear Mode with Quartz Tuning Fork Probes

“…Nevertheless, in the last few years some works have reported the use of QTF to image cells [27] and biomolecules [28], and for molecular recognition experiments [23,29], so the use of QTF for biological studies is increasing in popularity, but there is still a lack of information about protocols, benefits and drawbacks. In this work, we present the methodology to fabricate and use QTF for biological samples imaging, and some results obtained under different conditions (nitrogen, ambient and buffer) with different samples (bacteria, cells and biomolecules).…”