Microcantilever-Based Sensors:  Effect of Morphology, Adhesion, and Cleanliness of the Sensing Surface on Surface Stress

Abstract

The surface stress response of micromechanical cantilever-based sensors was studied as a function of the morphology, adhesion, and cleanliness of the gold sensing surface. Two model systems were investigated: the adsorption of alkanethiol self-assembled monolayers at the gas-solid interface and the potential-controlled adsorption of anions at the liquid-solid interface. The potential-induced surface stress, on a smooth and continuous polycrystalline Au(111)-textured microcantilever in 0.1 M HClO4, is in excellent agreement with macroscopic Au(111) single-crystal electrode results. It is shown that ambient contaminants on the sensing surface dramatically alter the surface stress-potential response. This observation can be misinterpreted as evidence that for polycrystalline Au(111) microcantilever electrodes, surface stress is dominated by surface energy change. Results for anions adsorption on gold are in contrast to the gas-phase model system. We demonstrate that the average grain size of the gold sensing surface strongly influences the magnitude of the surface stress change induced by the adsorption of octanethiol. A 25-fold amplification of the change in surface stress is observed on increasing the average gold grain size of the sensing surface from 90 to 500 nm.

High throughput optical readout of dense arrays of nanomechanical systems for sensing applications

“…This is related to changes in the electronic charge density at the underlying metal's surface. [60][61][62] From the change of curvature, we calculated the surface stress. A histogram of the surface stress is shown in Fig 4(c).…”

Piezoresistive cantilever array sensor for consolidated bioprocess monitoring

“…Godin et al investigated the origin of variation in the surface stress of fully gold-coated cantilevers and demonstrated that the deflection of a cantilever strongly depends on the surface roughness of the gold film (Godin et al 2004). The sensitivity and reproducibility of a cantilever's static response also depends on the uniformity and the molecular size of the immobilized functional layer and cleanliness of the sensing surface (Desikan et al 2007;Kim et al 2007;Tabard-Cossa et al 2007). Therefore, great care should be taken to prepare the microcantilever array sensor.…”

Piezoresistive measurement of Swine H1N1 Hemagglutinin peptide binding with microcantilever arrays

“…The sensitivity and reproducibility of a PM's static response would depend on the uniformity and the molecular size of the immobilized functional layer and cleanliness of the sensing surface. [10][11][12] Effective screen-to-detect systems such as the results presented here can help mitigate future outbreaks 13 by providing an "early warning" system preceding established disease containment plans. We have demonstrated that PM arrays can be used to specifically detect Swine-Origin Influenza A (H1N1) Hemagglutinin Peptide.…”