Eos rebel t1i

During this walking test, the participants were asked to perform a 5-m Timed Up and Go (TUG) test at their preferred walking speed while wearing a pair of accelerometers (Physilog^® IV, GaitUp, Switzerland) fixed on the top of their shoes. A total of six iTUG trials were administered of which the first three were without stimuli (“GVS off” trials) and the last three were with vestibular stimulation (“GVS on” trials). Such an order for trials was chosen to minimize any residual effect that vestibular stimulation might have in the subsequent trials. To remove any bias that subjects might have had toward the electric sensation, the study was designed as a single-blind experiment in which the subjects were not aware of the order of “GVS on” and “GVS off” tests. The electrodes were placed on participants’ skin and were connected to the stimulator during the entire data collection session. Sham stimulation was administered during the “GVS off” trials. The participants were told that the stimulus was always on with different degrees of intensity and, therefore, they might or might not feel the current during the trials. The iTUG trials were timed with a stop watch and also recorded with a camera (EOS Rebel T1i, Canon, Japan).

The tested samples had their edges taped onto a glass slide which was fixed to an optical mount. The illumination area of a collimated green laser with wavelength of 532 nm (Millennia Pro™, Spectra-Physics, USA) was expanded by a lens to cover the entire sample. The beam waist was measured by the knife-edge method. For actuator displacement analysis the beam waist radius was 4.32 mm. The total output power P_total of the laser was measured by an optical power meter (PM100A, Thorlabs GmbH, Germany). The received power (or input power, P_input) on the sample surface from a Gaussian laser beam was calculated by: $P_{\mathrm{input}}=\left(1-R\right){\int }_{-w/2}^{w/2}{\int }_{-l/2}^{l/2}{I}_0\exp \left(-\frac{2\left(x^2+y^2\right)}{r^2}\right)dxdy$ where R is the reflectance of the sample surface, r is the beam radius, I₀ is the intensity amplitude of the laser calculated by $I_0=2P_{\mathrm{total}}/\pi r^2$ for Gaussian beam profile, w and l are the sample width and length, respectively.
The illumination intensity (I) was calculated by: $I=P_{\mathrm{input}}/A$ where A is the area of the sample.
The deformation of the bilayer during actuation was recorded by a DSLR camera (Canon EOS rebel T1i) at a frame rate of 30 fps and the tip movement was analyzed using Matlab^®. The length of the samples (1 cm) was used to calibrate the pixel length in order to calculate the displacement. All the displacement measurements were performed at 20–25 °C and 20–30% RH.