Femtosecond laser ablation of gold interdigitated electrodes for electronic tongues

• Uniform gold interdigitated electrodes were fabricated by femtosecond laser ablation.
• Tradeoff between pulse energy and objective lens defined quality of interdigitated lines.
• The electrical properties of the gold interdigitated electrodes were evaluated by an e-tongue system.
• Laser ablation and photolithography electrodes are comparable in terms of electrode electrical performance.
• Laser ablation is a promising method for fabricating electrodes of varied geometries with resolution beyond the one achieved by conventional photolithography.

Electronic tongue (e-tongue) sensors based on impedance spectroscopy have emerged as a potential technology to evaluate the quality and chemical composition of food, beverages, and pharmaceuticals. E-tongues usually employ transducers based on metal interdigitated electrodes (IDEs) coated with a thin layer of an active material, which is capable of interacting chemically with several types of analytes. IDEs are usually produced by photolithographic methods, which are time-consuming and costly, therefore, new fabrication technologies are required to make it more affordable. Here, we employed femtosecond laser ablation with pulse duration of 50 fs to microfabricate gold IDEs having finger width from 2.3 μm up to 3.2 μm. The parameters used in the laser ablation technique, such as light intensity, scan speed and beam spot size have been optimized to achieve uniform IDEs, which were characterized by optical and scanning electron microscopy. The electrical properties of gold IDEs fabricated by laser ablation were evaluated by impedance spectroscopy, and compared to those produced by conventional photolithography. The results show that femtosecond laser ablation is a promising alternative to conventional photolithography for fabricating metal IDEs for e-tongue systems.