Jsm 6480lv sem

The corneal nipple arrays were studied using standard electron microscopy using eyes severed from heads of dead specimens. Eyes were dissected from insect heads and scales surrounding them were removed. Eyes were fractured in half with one half used for imaging the surface of the eye, the other for imaging a cross-section through a lens. Samples were mounted on SEM stubs using carbon tape and silver paint. The samples were sputter-coated with gold for surface imaging in a JEOL JSM6480LV SEM, or sputter coated with chromium for imaging in a JEOL JSM6310F FESEM.

A Zeiss Ultra 55 Field Emission Scanning Electron Microscope (FESEM) and a JEOL JSM-6480LV SEM were used for the study of the electrodes’ nanostructure. X-ray Photoelectron spectroscopy was performed on samples as received and after 60–480 seconds of Argon-ion etching at 4KV (0.7 μA of current) using an Oxford AXIS ULTRA instrument. Raman spectrum of the DLEG sample for confirming the formation of graphene from the polyimide during the engraving process was obtained by using a DXR2 Raman spectrometer from Thermo Scientific with a laser power of 5 mW, at a laser excitation of 514.5 nm, and 2 seconds of integration time. Energy-Dispersive X-ray Spectroscopy (EDS) of the sensor was implemented by using X-Mass from Oxford Instruments. No additional processing steps were performed on the sensors before the characterizations.

Prior to use, Au electrodes were
activated in 0.05 M H₂SO₄ by cycling the potential
from −0.5 to 1.6 V
versus Ag/AgCl for 12 cycles, at a scan rate of 100 mV s^–1. The PCB Au electrodes were functionalized with a film of hPG to
increase the surface area. The hPG film was deposited via the dynamic
hydrogen bubbling template as previously described by our group.¹⁵ The ESA of both the Au and hPG/Au electrodes
was calculated from the reduction peak of gold oxide in sulfuric acid,
as previously described.^{25 (link)}The Au
and hPG/Au electrodes were also characterized by scanning electron
microscopy (SEM) with the use of a JEOL JSM-6480LV SEM. Figure S1 shows the surface morphology of the
two electrodes.