Microfabricated electroosmotic pump for capillary-based sequential injection analysis

• Published in: Analytica chimica acta 2004-05, Vol.511 (1), p.105-112
• Main Authors: Pu, Qiaosheng, Liu, Shaorong
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Electric field decoupler; Electroosmotic pump; Exact sciences and technology; Galactosidase; General, instrumentation; Microfluidic chip; Sequential injection analysis
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2004.01.044

A microfabricated electroosmotic pump with an integrated serpentine isolation channel was developed on a glass chip and applied to a capillary-based sequential injection analysis (SIA) system for an enzyme inhibition assay. The pump chip contains an anode reservoir, an ion-exchange membrane electric field decoupler (EFD) that also serves as a cathode reservoir, parallel pump channels and an isolation channel. A two-step etching process was adopted to etch the pump channels to a depth of 20 μm and the isolation channel to a depth of 90 μm. The pump flow rate was very stable: the relative standard deviation (RSD) of the pump rate was 1.9% for propulsion and 2.3% for aspiration. The pump chip was successfully applied to a capillary-based sequential injection analysis system with a confocal fluorescence detector. For repetitive analysis of a 13 μM fluorescein solution, an RSD of 0.6% was attained, which demonstrated the flow stability of the EOF pump. The system was then applied to an enzyme inhibition assay, the diethylenetriaminepentaacetic acid (DTPA) inhibition of the β-galactosidase-catalyzed hydrolysis of fluorescein di(β- d-galactopyranoside). Reproducible results (RSD