A virtual valve for smooth contamination-free flow switching.
We present a channel geometry that allows for clean switching between different inlets of a microchip without any contamination of the inlets or the downstream flow. We drive this virtual valve with a pneumatic pressure setup that minimizes disturbance of the downstream flow during the switching procedure by simultaneous variation of the pressures applied to the different inlets. We assess the efficiency of the setup by spectroscopic measurement of downstream dye concentrations, and demonstrate its practical utility by sequentially constructing multiple layers of alginate hydrogel. The method is potentially useful for a whole series of further applications, such as changing perfusion liquids for cell culture and cell analysis, metering, chemical-reaction initiation and multi-sample chromatography, to name a few.
Braschler
Thomas
T
EPFL, LMIS 4, Station 17, BM3125, Lausanne, VD 1015, Switzerland. thomas.braschler@epfl.ch
Theytaz
Joel
J
Zvitov-Marabi
Ronit
R
van Lintel
Harald
H
Loche
Grazia
G
Kunze
Anja
A
Demierre
Nicolas
N
Tornay
Raphael
R
Schlund
Mario
M
Renaud
Philippe
P