Real-Time kHz to GHz Monitoring of Incubated Yeast Cell Growth Using Interdigitated Capacitors

This paper reports on long-term measurements of the growth of yeast cells using a vector network analyzer based approach. 20 μL of yeast cells in culture medium is trapped in a well on top of an interdigitated capacitor (IDC) sensor. The impedance is measured in the frequency range between 300 kHz up to 1 GHz over a period of 10 h. To minimize any environmental perturbation the IDC sensor is placed inside an in-house developed compact incubator, in which the humidity and temperature are precisely controlled. As a reference for the electrical measurements, two microscopes located on the top and the bottom of the IDC are used to optically inspect the cell growth in real-time. The correlation between the microscopic images and the changes in the Z
₁₁
reveals the well-known sigmoid relationship at lower frequencies but a linear relationship at higher frequencies. These results indicate that different polarization mechanisms are probed at different frequencies.