A Three-Dimensional Flow Control Concept for Single-Cell Experiments on a Microchip. 1. Cell Selection, Cell Retention, Cell Culture, Cell Balancing, and Cell Scanning

An ideal microchip for single-cell experiments should be
able to allow us to culture cells, to select any desired
single cell from a group, to retain the cell for convenient
cellular signal detection, and to deliver any buffer or
reagent directly to the cell at any time during continual
detection and observation. Most importantly, any negative
impact on the live cell should be minimized. To accomplish all these functions, we developed a three-dimensional liquid flow control concept and employed
special liquid flow fields to manipulate and retain a single
yeast cell freely in the chip. A zero-speed point was
controlled to retain the cell for three-dimensional cell
balancing and cell scanning. A dispersive flow delivered
reagents at a high speed to very near the cell and provided
them to the cell at a low speed. No force stronger than its
gravitational force was exerted on the cell, which could
be balanced on different positions on an arc-sloping wall,
thus minimizing any negative impact on the cell due to
strong liquid flows. Specifically, we demonstrate on-chip
single-cell culture, cell wall removal, and reagent delivery.
Subsequently, single-cell fluorescence detection was performed, and noise filtering and background correction
were applied for data processing.