This paper by Handel and Tournier, presented at the 2005 Joint IEEE International Frequency Control Symposium, examines quantum 1/f and classical phase noise in resonant bio-chemical MEMS sensors. The work analyzes both fundamental quantum noise sources and classical technical noise in microelectromechanical resonant sensors designed to detect biological molecules and chemical agents through mass loading or surface binding effects, providing comprehensive noise models for optimizing detection sensitivity, selectivity, and limit-of-detection in biomedical and environmental monitoring applications.