Abstract: Microelectromechanical (MEM) resonators are widely used as resonant sensors and oscillators in several areas of science and technology. Present MEM oscillators use an external feedback to sustain oscillations. In this presentation, I will discuss a MEM autonomous oscillator whose feedback is mediated by a direct current via the thermal-piezoresistive pumping mechanism. In contrast to traditional oscillators, this self-oscillator operates in its nonlinear regime, where the amplitude is self-limited by nonlinear stiffening and damping. We also study the thermomechanical noise spectrum of our device near the onset for self-oscillations, where we observe non-Lorentzian spectral broadening analogous to the onset of lasing or the ferromagnetic phase transition.

Bio: James Lehto Miller received his B.S. degree from Michigan State University and M.S. degree from Stanford University in mechanical engineering, in 2014 and 2016, respectively. He is currently pursuing the Ph.D. degree in mechanical engineering (Ph.D. minor in electrical engineering) at Stanford. His current research interests include nonlinearity and noise in micromechanical thermal-piezoresistive resonators, and magnetocaloric energy transport using inductive coupling.