<p>A microbalance that uses a microchannel resonator requires several samples to perform high-sensitivity measurements. However, multiple procedures are required to embed the resonator’s microchannels, which results in high fabrication costs. In this study, we establish a high-sensitivity mass measurement method based on the eigenmode shift in virtually-coupled stainless steel microchannel resonators. We use a pin-shaped electrode to excite the microchannel resonators via electrostatic force. The microresonator does not require semiconductor-specific fabrication equipment because we use a combination of metal etching and diffusion bonding to bury the channels. We combine this approach with the use of a virtually-coupled resonator with dynamics calculated in a computer and verify its effectiveness as a small mass measurement method. Self-excitation of the weakly coupled resonators induced by nonlinear feedback control compensates for increments in viscosity through corresponding increments in the internal viscosity. We measure the densities of distilled water, ethanol, and saline water to compare the sensitivities of methods using eigenfrequency and eigenmode shifts. Use of virtual coupling realizes eigenmode shifts that are two orders of magnitude higher than the corresponding eigenfrequency shifts.</p>