Development of a MEMS based dynamic rheometer

Abstract

Rheological methods that interrogate nanolitre scale volumes of fluids and solids have advanced considerably over the past decade, yet there remains a need for methods that probe the frequency-dependent complex rheological moduli through application of homogenous strain fields. Here we describe a Micro-Electro-Mechanical System (MEMS) based approach for the measurement of dynamic rheology of soft matter where oscillatory strain is produced in a sample sandwiched between an oscillating MEMS stage and a glass plate. The resulting stress-strain relationships are revealed by measurement and analysis of the stage motion. We present preliminary data on simple viscous fluids and on viscoelastic thin films. In this proof-of-principle device, we measure moduli in the range of 50 Pa to 10 kPa over a range of 3 rad s(-1) to 3000 rad s(-1) using less than 5 nL of sample material. The device's measurement window is limited primarily by our current ability to measure the motion of the stage. This device will provide a new way to characterize dynamic microrheology of an array of novel materials and will prove useful in a number of areas including biorheology, microfluidics and polymer thin films.

Actuation means for the mechanical stimulation of living cells via microelectromechanical systems: A critical review

“…Thermal expansion caused by electric currents heating up the material of a microstructure constitutes another well-known actuation principle used in MEMS (e.g., Zhu et al, 2006;Lu et al, 2006;Espinosa et al, 2007;Christopher et al, 2010). In particular, large rectilinear displacement parallel to the device substrate can be achieved with chevron (or V-shaped beam) configurations.…”

Design of a 1 DOF MEMS motion stage for a parallel plane geometry rheometer

“…Moreover, it would be advantageous to run multiple measurements at the same time of various composition of the paste to explore the influence of additives dosage or type on the cement paste rheological properties. Thus, a rheometer based on micro-electro-mechanical systems [8] would be advantageous. MEMS devices are small and low-cost [9, pp.…”

“…A MEMS-based linear motion stage replaces the oscillating plate in the parallel plate rotational rheometers, and uses an optical method to measure their motion [8]. The electrostatic actuators are commonly used in MEMS-based linear motion stages for their long range motions but need a clean environment for their operations [11]–[13].…”

Analysis of a Coupled-Mass Microrheometer

“…The issue is that only a few of the possible fluid geometries that can be realised in useful experimental set-ups lend themselves to analytical mathematical investigation. As such this causes, in the design of microrheometers, the analysis of the fluid mechanics to be highly idealised or restricted to simple cases (Christopher et al, 2010). Most microfluidic systems can be modelled in a numerical fashion, whether it is using finite element analysis, molecular dynamics or computational fluid dynamics (Sujatha et al 2008).…”

“…Recently a number of devices, known as microrheometers, have been fabricated with the ability to determine the properties of small samples of viscoelastic fluids (Cheneler, 2011, Crecea et al, 2009, Christopher et al, 2010. These devices are generally designed to dynamically manipulate isolated drops of fluid, usually contained in liquid bridges (Cheneler, 2011, Christopher et al, 2010, and are not in a form that is easily integrated into a commercial automated process, precluding highthroughput analysis.…”