Use of self-actuating and self-sensing cantilevers for imaging biological samples in fluid

Abstract

In this paper, we present a detailed investigation into the suitability of atomic force microscopy (AFM) cantilevers with integrated deflection sensor and micro-actuator for imaging of soft biological samples in fluid. The Si cantilevers are actuated using a micro-heater at the bottom end of the cantilever. Sensing is achieved through p-doped resistors connected in a Wheatstone bridge. We investigated the influence of the water on the cantilever dynamics, the actuation and the sensing mechanisms, as well as the crosstalk between sensing and actuation. Successful imaging of yeast cells in water using the integrated sensor and actuator shows the potential of the combination of this actuation and sensing method. This constitutes a major step towards the automation and miniaturization required to establish AFM in routine biomedical diagnostics and in vivo applications.

Nanotechnologies

“…AFM cantilevers have been actuated using a micro-heater at the bottom and integrated with deflection sensor as well as micro-actuator for imaging of soft biological samples in fluid (Fantner et al 2009). Influence of the water was investigated on the cantilever dynamics, the actuation and the sensing mechanisms, as well as the crosstalk between sensing and actuation.…”

Piezoresistive cantilevers for nanomechanical sensing

“…They demonstrated an imaging rate of one image per second with a resolution of 128 Â 128 pixels. The same group used a similar thermally actuated piezoresistive cantilever to demonstrate the imaging of biological samples in liquid [90] (Fig. 5a).…”

“…Mukhopadhyay et al used two and four cantilever arrays for DNA sequence sensing, by functionalising the gold-coated cantilevers with thiol-containing DNA single-Piezoresistive cantilevers for scanning probe microscopy. (a) Thermally actuated probe[90], Ó IOP Publishing. Reproduced by permission of IOP Publishing.…”

Atomic Resolution Disk Resonant Force and Displacement Sensors for Measurements in Liquid

“…For instance, using small oscillation amplitude (0.16-0.33 nm) of a ∼40 N/m cantilever, vertical resolution of 2-6 pm has been shown [5]. Piezoelectric and piezoresistive sensing, on the other hand, enable integration of sensing elements on the AFM cantilevers which significantly simplifies the experimental setup by eliminating the need for external sensing elements, precise system alignment and complex circuitry for operation [6]. However, such methods require complex fabrication processes and cannot compete with some of the conventional technologies in terms of sensitivity [6]- [8].…”

“…Piezoelectric and piezoresistive sensing, on the other hand, enable integration of sensing elements on the AFM cantilevers which significantly simplifies the experimental setup by eliminating the need for external sensing elements, precise system alignment and complex circuitry for operation [6]. However, such methods require complex fabrication processes and cannot compete with some of the conventional technologies in terms of sensitivity [6]- [8]. Taking advantage of high performance of microscale rotational mode disk resonators in liquid, this work presents an integrated and convenient (with fully electronic readout) force-displacement measurement technique that can be deployed in various environments (vacuum, air, and liquid) with higher sensitivities.…”