title: Biosensing enhancement using passive mixing structures for microarray-based sensors.
abstract: The combination of microarray technologies with microfluidic sample delivery and real-time detection methods has the capability to simultaneously monitor 10-1000 s of biomolecular interactions in a single experiment. Despite the benefits that microfluidic systems provide, they typically operate in the laminar flow regime under mass transfer limitations, where large analyte depletion layers act as a resistance to analyte capture. By locally stirring the fluid and delivering fresh analyte to the capture spot, the use of passive mixing structures in a microarray environment can reduce the negative effects of these depletion layers and enhance the sensor performance. Despite their large potential, little attention has been given to the integration of these mixing structures in microarray sensing environments. In this study, we use passive mixing structures to enhance the mass transfer of analyte to a capture spot within a microfluidic flow cell. Using numerical methods, different structure shapes and heights were evaluated as means to increase local fluid velocities, and in turn, rates of mass transfer to a capture spot. These results were verified experimentally via the real-time detection of 20-mer ssDNA for an array of microspots. Both numerical and experimental results showed that a passive mixing structure situated directly over the capture spot can significantly enhance the binding rate of analyte to the sensing surface. Moreover, we show that these structures can be used to enhance mass transfer in experiments regarding an array of capture spots. The results of this study can be applied to any experimental system using microfluidic sample delivery methods for microarray detection techniques.
authors: Institute of Photonics and Electronics, Chaberská 57, 18251 Prague, Czech Republic.
authors: N Scott
authors: NS
authors: Lynn
authors: Tecnológico de Monterrey, Eugenio Garza Sada 2501 Sur, C.P. 64849 Monterrey, N.L., México. Electronic address: israel@null.net.
authors: José-Israel
authors: JI
authors: Martínez-López
authors: Institute of Photonics and Electronics, Chaberská 57, 18251 Prague, Czech Republic.
authors: Markéta
authors: M
authors: Bocková
authors: Institute of Photonics and Electronics, Chaberská 57, 18251 Prague, Czech Republic.
authors: Pavel
authors: P
authors: Adam
authors: Centro de Investigación Científica y de Educación Superior de Ensenada, Unidad Monterrey, Alianza Sur No. 105, Nueva Carretera Aeropuerto Km 9.5, Apodaca 66629, N.L., México. Electronic address: vcoello@cicese.mx.
authors: Victor
authors: V
authors: Coello
authors: Tecnológico de Monterrey, Eugenio Garza Sada 2501 Sur, C.P. 64849 Monterrey, N.L., México. Electronic address: hector.siller@itesm.mx.
authors: Héctor R
authors: HR
authors: Siller
authors: Institute of Photonics and Electronics, Chaberská 57, 18251 Prague, Czech Republic. Electronic address: homola@ufe.cz.
authors: Jiří
authors: J
authors: Homola
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004277:DNA, Single-Stranded / Q000032:analysis; D004058:Diffusion; D004867:Equipment Design; D046228:Microarray Analysis / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
chemical_list: D004277:DNA, Single-Stranded
keywords: Biosensors; Mass transfer; Microarrays; Microfluidic mixing; Microfluidics