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Indexed by:期刊论文

Date of Publication:2009-09-07

Journal:SENSORS AND ACTUATORS B-CHEMICAL

Included Journals:SCIE、EI、Scopus

Volume:141

Issue:2

Page Number:646-651

ISSN No.:0925-4005

Key Words:Microfluidic; Microelectrocle; Thermal bonding; Plasma; PMMA

Abstract:Fracture of integrated metal microelectrodes likely happens during the thermal bonding process of PMMA [poly (methylmethacrylate)] microfluidic chips. In this paper, the fracture behaviors are studied. The fracture is mainly caused by the plastic deformation of the electrode plate (the PMMA plate with microelectrodes) and the thermal stress of microelectrodes, which is due to the high bonding temperature. To decrease the bonding temperature, a plasma assisted thermal bonding method is evaluated and first used to eliminate the fracture of microelectrodes. in this process. the surface of the cover plate (the PMMA plate with microchannels) is modified using oxygen plasma before the electrode plate is thermally bonded to the cover plate. The parameters of the oxygen plasma treatment are optimized, and the contact angle is decreased from 71.7 degrees to 43.6 degrees. The thermal bonding temperature is optimized, which decreases the temperature from 100 degrees C to 85 degrees C. Testing of bonding strength shows an average failure pressure of 1.75 MPa, which is comparable to the bonding strength of 1.46 MPa for chips bonded at 100 degrees C without plasma modification. In order to demonstrate this bonding method, a PMMA microfluidic chip with integrated copper interdigitated microelectrode arrays for AC electroosmotic pump is fabricated. (C) 2009 Elsevier B.V. All rights reserved.