Fig. 2: Characterization of ECORE sensitivity using PProDOT and PEDOT polymer thin films.
a Optical setup of ECORE using prism-coupled total internal reflection. M mirror, L lens, λ/2: half-wave plate, PBS polarizing beam splitter, BP bandpass filter, DPD differential photodetector, DPSS laser diode-pumped solid-state laser. Inset 1: photo of a cell culture device for ECORE measurement. Scale bar = 1 cm. Inset 2: The probing laser of 561 nm is focused to the prism with a spot size of ~25 μm (diameter at 1/e2 intensity). Images are false-colored and scale bar = 25 μm. b Schematic of the ECORE setup. A 561 nm probing laser is total-internally reflected at the interface of polymer and electrolyte solution. The electrochromic polymer thin film is modulated using a potentiostat based on a three-electrode configuration. RE reference electrode, CE counter electrode, WE working electrode. c Measured reflectance change, ΔR, of the four polymer thin films (top panel) when a train of 1 mV, 1 Hz squarewave potential is applied (bottom panel). d Measured reflectance change, ∆R·Pin (in microwatts), of different polymers as a function of incident laser beam power, I. e Measured reflectance change, ΔR, of different polymers as a function of applied potential. Measured reflectance change, ΔR, of different polymer films in response to 1 mV, 1 Hz squarewave potentials with respect to (f) different polymer film thicknesses, g different probing beam incident angles, and (h) under different bias potentials. Data are presented as mean ± SD; n = 55 squarewave cycles; PEDOT-epoly, PEDOT-spin, P(OE3)-D, and P(OE3)-E films are denoted as green hexagon, yellow triangle, pink circle, and blue diamond, respectively in (d–h). i Comparison of the reflectance change, ΔR, of the four polymer thin films in response to 1 mV, 1 Hz squarewave potential at zero bias. Data are presented as mean ± SD; n = 3 polymer films.
