Team Members:

Dr. Lawrence Kulinsky (Project Scientist)
Mr. Han Xu
Mr. Han-Kuan Tsai (Anthony)
Mr. Anuj Taneja
Mr. Xavier Casadevall i Solvas

Research Summary:

1. Polymer background

Conducting polymers show great potentials as electro-mechanical actuator materials. The actuation mechanism in the case of redox polymers is based on the migration of ions in and out of the polymer during redox cycling. Among other polymers, Polypyrrole is a material of choice. Polypyrrole actuators in particular can generate a strain of 1%-3% under proper electrochemical excitation, thereby generating a high stress (100-1000 times greater than a skeletal muscle). They require low voltage for actuation (1 V or less), are biocompatible, and operate ideally in liquid electrolytes (including biofluids). All these features make them very promising for biomedical applications.

2. Resent Results

our lab is currently working on responsive drug delivery applications of polymer actuators. We are making arrays of drug reservoirs covered with small polymer valves. A biosensor controls the opening and closing of the valves, and the required amount of drug is released. To minimize valve leakage and to simplify the fabrication of the polymer actuators. We are doing research on new polymer actuator array designs and alternative fabrication methods.

Figure 1: Movement of an actuator made of one layer of polypyrrole and one layer of Au. Left ) The bilayer is straight under no current. Right ) The bilayer is bent to the liquid surface after -1V (vs Ag/AgCl) applied for 4 seconds. Actuator size: 4mm*12mm; film thickness: polypyrrole-20um, Au-200nm; working solution: 0.1M NaDBS.

Figure 2: Movement of a column of actuators made of PPy/Au bilayer on the polyimide substrate. Left) Closing position under -1V (vs Ag/AgCl). Right) Opening position without current. Actuator size: 1mm*3mm; film thickness: polypyrrole-20um, Au-200nm; working solution: 0.1M NaDBS.

References:

[1] G. G. Wallace, G. M. Spinks, P. R. Teasdale, Conductive Electroactive Polymers: Intelligent Materials Systems, Technomic, Lancaster, UK 1997.

[2] E. Smela, “Conjugated Polymer Actuators for Biomedical Applications”, Advanced Materials, 15, No. 6, (2003) pp481-494.

[3] S. Deo, E. A. Moschou, S. F. Peteu, P. Eisenhardt, L. G. Bachas, M. Madou, S. Daunert, “Responsive Drug Delivery Systems”, Analytical Chemistry, 75 (9), pp207-213.