Supplemental Information for:

ToF-SIMS Characterization of Silk Fibroin and Polypyrrole Composite

Actuators

Nathan P. Bradshaw,1 Sean Y. Severt,1 Zhaoying Wang,3 Carly V. Klemke,2

Jesse D. Larson,1 Zihua Zhu,3 Amanda R. Murphy,1 and Janelle M. Leger.2,*

Cyclic Voltammetry. Cyclic voltammetry experiments were carried out using a Pine Research Instrumentation WaveNow potentiostat, and data were recorded and analyzed using AfterMath software. Counter and reference electrodes were purchased from Bioanalytical Systems, Inc. A 3-electrode cell equipped with a platinum wire counter electrode, and an Ag/AgCl reference electrode was used. Rectangular films (5 mm x 13 mm) coated with PPy served as the working electrode. Contact was made to the films using copper tape that was encapsulated in Kapton® tape to allow the film to be completely submerged into the electrolyte. The area of film exposed to electrolyte was approximately 65 mm2. CV scans were carried out in an aqueous supporting electrolyte solution of phosphate buffered saline (PBS, 0.1 M phosphate, 0.15 M NaCl). Scans were initiated at 0 V and swept between ±1.0 V at a scan rate of 50 mV/s.

Figure 1. Cyclic voltammogram of a bilayer actuator film in phosphate buffered saline solution.

Figure 2: Illustration of the actuator setup during free end bending actuation. To make electrical contact, a plastic clamp is used to press the film against a gold foil. The majority of the film is then submerged in an electrolyte solution.

Figure 3: A representative negative ion mass spectrum recorded during a single sampling of ions.

Figure 4: Molecules assigned to peaks of interest from the IPN mass spectrum. pTSA (m/z = 171) and benzenesulfonic acid radicals (m/z = 156).

Figure 5: Current response and stress generated during actuation for a representative device.