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

Abstract

A nano-cheese-cutter to directly measure interfacial adhesion of freestanding nano-fibers J. Appl. Phys. 111, 024315 (2012) Stabilization and growth of non-native nanocrystals at low and atmospheric pressures J. Chem. Phys. 136, 044703 (2012) Nanoparticle production in arc generated fireballs of granular silicon powder AIP Advances 2, 012126 (2012) Stability and topological transformations of liquid droplets on vapor-liquid-solid nanowires J. Appl. Phys. 111, 024302 (2012) Role of RuO3 for the formation of RuO2 nanorods Appl. Phys. Lett. 100, 033108 (2012) Additional information on Rev. Sci. Instrum. We present an instrument based on the scanning of a laser beam and the measurement of the reflected beam deflection that enables the readout of arrays of nanomechanical systems without limitation in the geometry of the sample, with high sensitivity and a spatial resolution of few micrometers. The measurement of nanoscale deformations on surfaces of cm 2 is performed automatically, with minimal need of user intervention for optical alignment. To exploit the capability of the instrument for high throughput biological and chemical sensing, we have designed and fabricated a two-dimensional array of 128 cantilevers. As a proof of concept, we measure the nanometer-scale bending of the 128 cantilevers, previously coated with a thin gold layer, induced by the adsorption and self-assembly on the gold surface of several self-assembled monolayers. The instrument is able to provide the static and dynamic responses of cantilevers with subnanometer resolution and at a rate of up to ten cantilevers per second. The instrumentation and the fabricated chip enable applications for the analysis of complex biological systems and for artificial olfaction.

Tackling reproducibility in microcantilever biosensors: a statistical approach for sensitive and specific end-point detection of immunoreactions

“…The surface stress is derived by fitting the curves to a second-order polynomial and applying the Stoney's equation 26,37,38 . This method requires an accurate determination of the cantilever thickness that can change up to 10% with respect to the nominal value 34 . Here, we measure the resonant frequency of the cantilever in order to calculate the thickness, and thus obtain a more accurate surface stress value 34 .…”

“…The cantilevers are 500 µm long, 100 m wide and 1 m thick. The nanometer-scale out-ofplane displacements of the cantilevers were measured in air at room temperature by scanning laser beam deflection microscopy [34][35] (Figs. 1(a) and 1(b)).…”

“…In addition, the size of these devices has been increasingly reduced which leads to higher device density and, more importantly, implies higher sensitivity. In addition, high throughput detection can readily be achieved by fabricating hundreds of cantilevers in arrays and by the fast read-out of their response by optical 14,[33][34][35] or electrical techniques 13,25 .…”

Gold coating of micromechanical DNA biosensors by pulsed laser deposition

“…The surface topography of the gold-coated sensors was also characterized by AFM (Nanoscope V Multimode, Veeco Instruments Inc.) and their mechanical response to temperature variations by using a SCALA device (Mecwins S.L., Madrid, Spain), a platform capable of fast deflection sensing and full 3D characterization of micromechanical sensors of any size. 19,20 During these experiments, the temperature was changed at a rate of about 0.14 C per minute, and the relative humidity (RH) was kept at 0%. Following the immobilization procedure, the sensors were vigorously rinsed in Milli-Q water, at room temperature to discard unspecific interactions, and were dried under dry nitrogen flow.…”

“…A 20 nm thick gold layer was chosen as optimum for coating the micromechanical sensors and their differential stress, in response to temperature changes was characterized by using a scanning laser analyzer (SCALA). 19,20 We analyzed the performance of the gold-coated micromechanical sensors in comparison to those fabricated by the conventional method of thermal evaporation used in previous work. 17 For that purpose, we measured the mechanical response upon hydration, before and after the adsorption of self-assembled doublestranded DNA (dsDNA) monolayers.…”