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

Abstract

Quartz tuning forks are extremely good resonators and their use is growing in scanning probe microscopy. Nevertheless, only a few studies on soft biological samples have been reported using these probes. In this work, we present the methodology to develop and use these nanosensors to properly work with biological samples. The working principles, fabrication and experimental setup are presented. The results in the nanocharacterization of different samples in different ambients are presented by using different working modes: amplitude modulation with and without the use of a Phase-Locked Loop (PLL) and frequency modulation. Pseudomonas aeruginosa bacteria are imaged in nitrogen using amplitude modulation. Microcontact printed antibodies are imaged in buffer using amplitude modulation with a PLL. Finally, metastatic cells are imaged in air using frequency modulation.

Finite Element Analysis of Electrically Excited Quartz Tuning Fork Devices

“…QTFs are piezoelectric devices that are commonly known for their application in customer electronics. In 1989, QTFs started to be used in microscopy [11–14]. One great advantage is the ability to combine the functions of a sensor and actuator, thus reducing the overall instrument complexity.…”

Quartz tuning fork-based conductive atomic force microscope with glue-free solid metallic tips

“…Electrical excitation is the proper way to drive a QTF as a force nano-sensor if quantification of the QTF mechanical measurements is needed [29]. A constant tip-sample distance is maintained throughout the QTF frequency shift measurement using the electronics developed and presented in our previous work [24].…”

Contributed Review: Quartz force sensing probes for micro-applications

“…Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Download to IP: 134.157.80. increasing the value of Q affects sensitivity on given systems, 17 with some works reporting increased accuracy and others that it is counteracted by greater thermal noise. It must also be pointed out that Q-control only works for the tapping or shear-force modes in amplitude modulation, which use a given signal frequency (AM-AFM, later described in Section II D).…”