The use of oscillators in science and technology has proven to be very impactful due to established mathematical concepts that laid the foundation for high accuracy measurements. In this thesis, I present how we used photo-thermally actuated mechanical oscillators to measure the mass and frequency-dependent mechanical properties of single, living cells with high accuracy and temporal resolution. We found that virus-infected cells stop cell growth, as well as that cell mass fluctuates within seconds by about 20 picograms which we could link to cellular water transport. Moreover, we could demonstrate the power-law behaviour of rounded cells up to a frequency of 40 kHz
