title: Centimeter-Scale Surface Interactions Using Hydrodynamic Flow Confinements.
abstract: We present a device and method for selective chemical interactions with immersed substrates at the centimeter-scale. Our implementations enable both, sequential and simultaneous delivery of multiple reagents to a substrate, as well as the creation of gradients of reagents on surfaces. The method is based on localizing submicroliter volumes of liquids on an immersed surface with a microfluidic probe (MFP) using a principle termed hydrodynamic flow confinement (HFC). We here show spatially defined, multiplexed surface interactions while benefiting from the probe capabilities such as non-contact scanning operation and convection-enhanced reaction kinetics. Three-layer glass-Si-glass probes were developed to implement slit-aperture and aperture-array designs. Analytical and numerical analysis helped to establish probe designs and operating parameters. Using these probes, we performed immunohistochemical analysis on individual cores of a human breast-cancer tissue microarray. We applied α-p53 antibodies on a 2 mm diameter core within 2.5 min using a slit-aperture probe (HFC dimension: 0.3 mm × 1.2 mm). Further, multiplexed treatment of a tissue core with α-p53 and α-β-actin antibodies was performed using four adjacent HFCs created with an aperture-array probe (HFC dimension: 4 × 0.3 mm × 0.25 mm). The ability of these devices and methods to perform multiplexed assays, present sequentially different liquids on surfaces, and interact with surfaces at the centimeter-scale will likely spur new and efficient surface assays.
authors.affiliation: IBM Research-Zürich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
authors.forename: David P
authors.initials: DP
authors.lastname: Taylor
authors.affiliation: IBM Research-Zürich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
authors.forename: Ismael
authors.initials: I
authors.lastname: Zeaf
authors.affiliation: IBM Research-Zürich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Lovchik
authors.affiliation: IBM Research-Zürich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
authors.forename: Govind V
authors.initials: GV
authors.lastname: Kaigala