Aveek N. Chatterjee

Development and modeling of electrically triggered hydrogels for microfluidic applications

In this paper, we present progress in the development of electrically triggered hydrogels as components in microfluidic systems. Stimuli-responsive hydrogels are fabricated using liquid-phase photopolymerization techniques and are subjected to different voltage signals in order to determine their volume change response characteristics. A chemoelectromechanical model has been developed to predict the swelling and deswelling kinetics of these hydrogels. The Nernst-Planck equation, Poisson equation, and mechanical equations are the basic governing relationships, and these are solved in an iterative manner to compute the deformation of the hydrogel in response to varied electrical input.

Combined circuit/device modeling and simulation of integrated microfluidic systems

A combined circuit/device model for the analysis of integrated microfluidic systems is presented. The complete model of an integrated microfluidic device incorporates modeling of fluidic transport, chemical reaction, reagent mixing, and separation. The fluidic flow is generated by an applied electrical field or by a combined electrical field and pressure gradient. In the proposed circuit/device model, the fluidic network has been represented by a circuit model and the functional units of the /spl mu/-TAS (micro Total Analysis System) have been represented by appropriate device models. We demonstrate the integration of the circuit and the device models by using an example, where the output from the fluidic transport module serves as the input for the other modules such as mixing, chemical reaction and separation. The combined circuit/device model can be used for analysis and design of entire microfluidic systems with very little computational expense, while maintaining the desired level of accuracy.

Dissolvable hydrogels as transducers of bio-chemical signals: models and simulations

Hydrogels have a large number of applications in microelectromechanical systems (MEMS) technology as sensors and actuators. In this paper we investigate the use of responsive micro-sized hydrogels as transducers of biochemical signals. Hydrogels, crosslinked via disulfide bonds, when immersed in a solution containing a disulfide reducing agent can dissolve as the covalent cross-links are cleaved by the reducing agent and thereby indicate the presence of the cleaving agent. As a result, this phenomenon leads to the transduction of chemical signal to visual signal. The mechanism of the hydrogel dissolution process has been studied in detail and a mathematical model has been developed. From the vanishing time of the dissolvable hydrogel, a significant amount of information about the surrounding bath solution can be obtained.