Ionic Electroactive Polymer Actuators for On-Chip Sample Processing Integrated With Microflow Cytometer

As interest in and potential uses for microfluidic and optofluidic analytical techniques grows, the need for on-chip, automated sample processing becomes increasingly important because this aspect is critical to allowing the devices to be commercially feasible and practical. One such design that implements on-chip processing is using ionic electroactive polymer (IEAP) actuators to perform mixing of particles in the microchannel and using a single magnet positioned beneath the channel to trap the magnetic beads. IEAP actuators consist of a central ionic membrane with conductive network composite (CNC) layers on either side. Gold electrodes placed on the outside of CNC layers are connected to a metal anode and cathode. When subjected to an electric field, the ions in the actuator move, electromechanically causing the entire length of the actuator to flex [1]. Although most actuators to date have been developed for use in air rather than in solutions, we have adapted previously developed actuators by optimizing their electromechanical functions to suit our needs and coating them in a protective film. The actuators are embedded in a microchannel in different configurations, which are then tested to determine which configuration most effectively trapped, mixed, and released the magnetic beads. The most effective configuration will subsequently be used to perform automated sample processing for an assay.

The Effect of Ionic Liquid Uptake and Self-assembled Conductive Network Composite Layers on NafionTM based Ionic Polymer Metal Composite Electromechanical Bending Actuators

ABSTRACTIonic liquid (IL) is used as the working electrolyte in ionic polymer metal composite (IPMC) electromechanical bending actuators because of its high stability and conductivity, which are crucial for the consistency and speed of the actuation. Because the bending actuation is caused by the migration and accumulation of the cations and anions of the IL, it is clear that both the overall number of ions and the effectiveness of ion transport and accumulation play important roles in the actuation behavior. In this paper, the effect of enhancing the ion accumulation by the self-assembled conductive network composite (CNC) layers is investigated by comparing the bending behavior of actuators with and without CNC layers. In addition, IPMC actuators with various IL uptakes are also tested in order to study the dependence of the bending performance on the amount of the ions available. It is found that, with the CNC layers, the maximum bending curvature of the actuator increases with increased IL, which shows the crucial role played by the IL. However, under the same conditions, the performance improvement of actuators without CNC layers saturates when the IL uptake reaches around 10% wt. This demonstrates the role of the CNC layers to provide a porous electrode with increased capacitance that thus accommodates accumulation of more ions near the electrodes, which in turn boosts the overall bending curvature of the actuator.