Vls2.30dt

LIG working electrodes were designed in CorelDraw consisting of a circular working area (3.0 mm) connected to a stem (14.3 × 2 mm) that leads to a bonding pad area (2.9 × 2.5 mm) based on previous work^{19 (link),46 (link)}. In summary, LIG electrodes were engraved on Kapton film using a CO₂ laser (VLS2.30DT, Universal Laser Systems, Inc., Scottsdale, AZ, US) at 75% speed, 40% power, and 1000 PPI. A passivation layer of nitrocellulose lacquer was applied to the stem area, and a metallic tape was incorporated into the bonding pad area of the working electrode. Platinum nanoparticles (nPt) were coated on the working electrode via electrodeposition by immersing the working electrode in a solution of 1.44% (v/v) chloroplatinic acid and 0.002% (v/v) lead acetate and applying a constant potential of 10 V for 90 s, as described by Moreira et al. (2022).

A serpentine-patterned LIG (Figure 7) was fabricated directly onto a commercial PI film (125 μm-thick Kapton polyimide film, DuPont, Wilmington, DE, USA) with a CO₂ laser system platform (VLS 2.30DT, power P_max = 30 W, speed S_max = 1270 mm·s⁻¹, and wavelength λ = 10.6 μm, Universal Laser Systems, Scottsdale, AZ, USA). The two circle shapes on the LIG were formed on each top and bottom edge to provide electrical connections. The optimized laser parameters were a laser power of 4 W, a scanning speed of 127 mm·s⁻¹, and an image density of 500 pulses per inch (PPI, 1 inch = 25.4 mm); these parameters were used for fabricating all of the devices. The desired pattern was designed via AutoCAD and CorelDRAW.