We report on measurements of the growth rate of single budding yeasts with two microfluidic devices. One device is a MOSFET-based microfluidic Coulter-type sensor, which amplifies nonlinearly the resistance modulation from the translocation of budding yeast through the sensing microchannel. By moving a budding yeast cell back and forth through the sensing channel and measuring the induced resistance pulse from the translocation of the budding yeast, the volume growth rate of a budding yeast cell can be measured over its whole cell cycle. The other microfluidic device is based on comparing the resistance of the sensing microchannel with that of a reference microchannel, which eliminates the signal drift from the electrical conductivity change of the culture media. The reference channel-based sensing scheme enables real-time measurements of the volume growth rate of a budding yeast cell sitting in the sensing microchannel over a whole cell cycle. Measurement results from both devices show that the volume growth of single budding yeast is of sigmoid shape with a slow growth rate both before the bud emergence and at the end of the cell cycle. The device could be used for other important applications such as sensing the response of kidney cells to their micro-environments.

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