Simultaneous oscillation and frequency tracking of multiple resonances via digitally implemented phase-locked loop array

A measurement system comprising:

• one or more suspended microchannel resonators, each resonator comprising a fluid channel for flowing a carried substance therethrough;
• an excitation element for driving the one or more resonators;
• a sensor for monitoring motion of the one or more resonators;
• at least one phase locked loop (PLL) in feedback between the excitation element and the sensor, wherein the PLL is configured to operate at or near a resonant mode of the one or more resonators;
• and
• a processor for determining information from PLL internal signals indicative of a resonator frequency shift
• wherein the system is configured to determine one or more properties of the carried substance on the one or more resonators by measuring the resonator frequency shift due to the presence of the carried substance as the carried substance flows through the fluidic channel on the one or more resonators, and
• wherein the transfer function of the PLL is configurable for shape and bandwidth.