Pranjal Sarma* and Promod Kumar Patowari Pages 137 - 147 ( 11 )
Background: Micromixers having various simple and complex microchannels is an inevitable part of almost all the microfluidic devices and circuitries nowadays. Particularly the metallic micromixers are very important for many chemical and process industries. Fabrication of metallic microchannels still remains a challenging task.
Objective: The work focuses on the fabrication of microchannels of different geometries and intrinsic features on metals. Here, an alternate approach for fabricating microchannel in metals is demonstrated which is easy and doesn’t demand a very high level of expertise.
Method: The fabrication is carried out using Wire-Cut Electric Discharge Machine (WEDM) and Electric Discharge Machine (EDM) and accomplished in two stages: 1) Micro-tool fabrication in WEDM; 2) Microchannel machining in EDM. Parametric investigation of the processes is also carried out for understanding the influence of different parameters in microfabrication.
Results: Different serpentine micromixer configurations are fabricated on copper and aluminum. Open channel configuration of metallic micromixers of average microchannel width 400 μm is fabricated as per the design. During micro-tool fabrication in WEDM, parametric conditions: pulse on time 25 µs, pulse off time 6 μs, input current 1 A and wire feed rate 75 mm/min gave optimal results among the investigated parametric combinations. During the second stage of microfabrication using EDM, the effect of input parameters, viz. input current, pulse on time and pulse off time on the output parameters viz. machining time, overcut, edge deviation and tool depletion are investigated. Results highlight the importance of careful selection and control of all these process parameters for manufacturing metallic microchannels by EDM.
Conclusion: The proposed method is able to give rise to micro-features like microchannel on metals with reasonable ease and accuracy. The fabricated micromixers can be used for Lab on Chip (LOC), Point of Care (POC) devices or/and microreactors. The metallic micromixers can be used to handle various corrosive species and reagents which the conventional polymeric substrate can’t handle. Thus it can lead to further advancement in the field of microfluidics.
Microfabrication, open channel, micromixer, microchannel, microfluidics, WEDM, EDM.
Department of Mechanical Engineering, School of Technology, Assam Don Bosco University, Guwahati, Assam 781017, Department of Mechanical Engineering, National Institute of Technology, Silchar, Assam 788010