Christopher B. Burgner

Comparison of parametric and linear mass detection in the presence of detection noise

We experimentally investigate the performance of a nonlinear parametrically driven mass sensor in the presence of detection noise. Mass detection is achieved by measuring the amount of methanol vapor adsorption on the sensor. To demonstrate the advantage of parametric sensing in counteracting the influence of detection noise, we operate the sensor in both the parametric and harmonic resonance mode. Comparison of the results shows that in contrast to conventional linear harmonic sensing, the detection sensitivity does not deteriorate for the parametric case when a tenfold increase in detection noise is introduced. Furthermore, we demonstrate additional functionality of the parametric sensor by utilizing it as a threshold detector, whose performance remains the same despite the added detection noise. Taken together, these results suggest that for mass detection in the presence of detection noise, a parametrically operated sensor may offer better performance over one operated harmonically in the linear regime.

Control of MEMS on the edge of instability

This paper investigates a new method for tracking parameters at which dynamic bifurcations occur in MEMS based on state statistics of a resonator. Experimental results show that observed changes in phase and amplitude precede a sub-critical pitchfork bifurcation. Feedback control, based on the statistics of the phase, is then employed to stabilize a device on the edge of instability. Sensitivity to changes in device parameters is explored and initial results show high sensitivity is obtained for low vibration amplitudes. Furthermore, experimental results on the same device using an older method of bifurcation sensing show acquisition rate improvement by over three orders of magnitude with the new method.

Noise Squeezing Controlled Parametric Bifurcation Tracking of MIP-Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing

This paper reports real-time explosive gas sensing (DNT) in atmospheric pressure utilizing the noise squeezing effect that occurs before a bifurcation event. A noise-squeezing controller based on the statistics of phase noise is implemented using high-speed LabVIEW field programmable gated array. A high frequency TNT-molecularly imprinted fixed-fixed microbeam sensor utilizes this nontraditional sensing strategy and performs DNT sensing at various concentrations. Experiments are conducted using both noise-based and sweep-based bifurcation tracking for a direct comparison. Results demonstrate noise-based bifurcation tracking is not only capable of performing reliable frequency tracking, but also show the method is superior to the bifurcation sweep-based tracking. Over three orders of magnitude improvement in acquisition rate is achieved, and as a result, confidence and precision on bifurcation frequency estimation is significantly improved over the bifurcation sweep tracking method, enabling DNT sensing at concentrations much below sub-ppb (parts-per-billion) level.

Using nonlinearity to enhance micro/nanosensor performance

Resonant microelectromechanical systems are key building blocks for many microsensor applications, including mass detection, inertial detection and RF filters and timing oscillators. Especially in systems with low damping, amplitudes are such that nonlinearities are present. In many applications, these nonlinearities can be significant, and need to be accounted for. In this paper, mass sensing of DNT will be discussed in the context of an application where understanding and cleverly utilizing nonlinearity results in improved sensor performance.

Nonlinear dynamics of MEMS systems

Parametric resonance and bifurcation sensing has been utilized for a number of applications in MEMS (microelectromechanical systems), including mass detection, RF oscillators/filters and inertial sensing. Nonlinearities are very important in these applications, where often the device is actually operating in a nonlinear regime. Microcantilevers which monitor mass change as a way perform chemical detection is not a new idea. In the linear, harmonic implementation, this has been demonstrated by many. We present a sensor that utilizes nonlinear stability be‐havior to achieve reliable quantitative chemical gas sensing and threshold detec‐tion in a noisy environment. This sensor, while comparable in ultimate sensitivity in vacuum environments, demonstrates the benefit of nonlinear operation when operating in noisy environments. Sensor feasibility is demonstrated experimentally in air through the sensing and detection of methanol. Additionally we discuss the effects of noise, and the strategies to improve sensi...

Characterization of a Novel MEMGyroscope Actuated by Parametric Resonance

We present a novel scheme for a robust micro gyroscope excited parametrically that reduces the sensitivity loss due to mismatching in the drive and the sense natural frequencies, which is a common problem in micro gyroscopes based on harmonic oscillators. We demonstrate experimentally that sing a parametric resonance based actuator, the drive-mode signal has rich dynamic behavior with a large response in a large bandwidth. In this way the system is able to induce oscillations in the sense-mode by Coriolis force coupling, despite a clear disparity on their fundamental frequencies. Thus we propose a micro gyroscope that is less sensitive to parameter variations due to its inherent dynamical properties.Copyright

Using Parametric Resonance to Improve Micro Gyrsocope Robustness

Knowing that mismatching between orthogonal modes is a common problem in micro gyroscopes based on harmonic oscillators, we have explored a different actuation mechanism based on parametric resonance, therefore reducing the sensitivity loss due to mismatching in the drive and the sense natural frequencies. We demonstrate experimentally that using a parametric resonance-based actuator, the drive-mode signal has rich dynamic behavior with a large response in a large bandwidth. In this way the system is able to induce oscillations in the sense-mode by Coriolis force coupling, despite a clear disparity on their fundamental frequencies. Thus we propose a micro gyroscope that is less sensitive to parameter variations due to its inherent dynamical properties.