An innovative patternable microelectrode bonding technology for high-performance and cost-effective sealing in microfluidic chips

Microfluidic chips pose as an interdisciplinary frontier as they integrate various fields, while typically serving as a novel technological platform for precise manipulation of minute liquid volumes and biological analysis. However, the chase for enhanced bonding quality in order to fabricate these chips correctly, has led to the use of increasingly complex technology, limiting the marketability of microfluidic products. In this work, a novel microelectrode bonding technology is proposed, which addresses the demands for reliable, low-cost, and high-throughput bonding. The proposed process utilizes the Joule heating effect of microelectrodes at low voltages, in order to rapidly generate sufficient heat and allow for the successful bonding of the chip. The material used for the microelectrodes is nickel, and the method chosen for their fabrication is small-batch electrodeposition. The microelectrodes and microchannels morphology are characterized by Extended Depth of Field Microscopy, while the quality of heating produced is assessed by a high-speed infrared camera. The finalized bonding strength is characterized by measuring the microchannel burst pressure, using an apparatus comprising of a syringe pump, a precision pressure gauge, and a connecting tubing. The results prove that this is a rapid polymer bonding method, which uses less than 3 Volts. Additionally, the results underscore the process’s effectiveness, yielding chips with burst strengths over 2.9 MPa, while microchannel deformations are kept under 10 %. Finally, the advantages of the technology are discussed and its limitations are eliminated by further conceptualization. The proposed method uses no chemicals or contaminants, nor complex equipment, rendering it simple, green, and sustainable. This paves the way for the development of new efficient and greener paradigms, aiming towards leading engineering and manufacturing to a sustainable future.