Dynamic trapping of single cells. (a) Illustration of the suspended microchannel resonator (SMR) trapping a single cell. Embedded channel cross-sections for bacteria, yeast and mammalian L1210 mouse lymphoblasts are 3 × 8 microns, 8 × 8 microns, and 15 × 20 microns, respectively. The silicon walls are opaque except in the 15 × 20 microns device, which has thinner walls. (b) Schematic of fluidics: sample is injected in parallel through the left and right inlets (IL and IR) and collected at the left and right outlets (OL and OR). While trapping, IL, IR and OL are kept at the same constant pressure; variable pressure at OR applied by a computer controlled regulator determines the direction of fluid flow in the device. (c) Raw data showing 400 measurements of one B. subtilis cell’s buoyant mass. The frequency shift increase with time indicates cellular growth. inset Detail of a few peaks that show a locally stable baseline forms after each pass through the SMR, allowing for drift compensation. (d) Several B. subtilis cells were sequentially trapped. Each point represents the amplitude of the frequency shift, converted to buoyant mass, as the cell transits through the cantilever. Each set of points (e.g. from 0 to 12 minutes) is one single cell or non-segregated cells. Heavier cells have higher growth rates.