The Manalis Laboratory weighs single cells

using the lab's suspended microchannel resonator.

The resonator, which is about the size of a human hair,

vibrates at a certain frequency.

When a cell passes through the resonator,

the frequency changes by an amount proportional

to the weight of the cell.

To measure the mass, volume, and density of a cell,

we load the device with two different fluids,

the blue fluid containing cells, and the yellow fluid,

which has a different density than the blue fluid.

A cell passes through the cantilever

and we measure the cell's weight while it's

surrounded by the blue fluid.

The cell then enters the yellow fluid,

the direction of fluid flow is reversed,

and we measure the cell's wait a second time, this time

while it's surrounded by the yellow fluid.

From these two weight measurements

we can calculate the mass, volume, and density

of a cell every five seconds.