Introduction of a co-resonant detection concept for mechanical oscillation-based sensors.

Micro- and nanoelectromechanical oscillators driven at or close to their resonance frequency are used as sensors in many fields of science and technology. A decrease in the oscillator's effective spring constant and/or mass holds great potential for an increase in the sensor's sensitivity. This is usually accompanied by a reduction in spatial dimensions, which in most cases requires more complex detection methods. By analyzing the complex behavior of a simple asymmetric coupled harmonic oscillator model we propose a novel sensor concept which combines the advantages of bigger and smaller oscillators, i.e. ease of detection and high sensitivity. The concept is based on matching the resonance frequencies of two otherwise very different oscillators. To support our theoretical considerations, we present an experimental implementation of such a sensor and respective experimental data, verifying a substantial signal enhancement by several orders of magnitude.