Thin-film IrOx pH microelectrode for microfluidic-based microsystems.
Microsensors are valuable tools to monitor cell metabolism in cell culture volumes. The present research describes the fabrication and characterization of on-chip thin-film iridium oxide pH microsensors with dimensions of 20 microm x 20 microm and 20 microm x 40 microm suitable to be incorporated into nl volumes. IrOx thin films were formed on platinum microelectrodes by electrochemical deposition in galvanostatic mode. Anodically grown iridium oxide films showed a near super-Nernstian response with a slope of -77.6+/-2 mV/pH at 22 degrees C, and linear responses within the pH range of 4-11. Freshly deposited electrodes showed response times as low as 6s. Long-term studies showed a baseline drift of 2-3 mV/month, which could easily be compensated by calibration. This work demonstrated for the first time the use of planar IrOx pH microelectrodes to measure the acidification rate of CHO and fibroblast cells in an on chip cell culture volume of 25 nl with microfluidic control.
Ges
Igor A
IA
Department of Biomedical Engineering, Vanderbilt University, 6301 Stevenson Center, VU Station B 351631, Nashville, TN 37235-1631, USA.
Ivanov
Borislav L
BL
Schaffer
David K
DK
Lima
Eduardo A
EA
Werdich
Andreas A
AA
Baudenbacher
Franz J
FJ
D000818:Animals; D016466:CHO Cells; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005347:Fibroblasts / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017736:Ion-Selective Electrodes; D007495:Iridium / Q000032:analysis / Q000737:chemistry*; D008567:Membranes, Artificial; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D008904:Miniaturization
D008567:Membranes, Artificial; C044458:iridium oxide; D007495:Iridium