&lt;title&gt;Optical measurement of LIGA milliengine performance&lt;/title&gt;

Dickey, Fred M.; Holswade, Scott C.; Christenson, Todd R.; Garcia, Ernest J.; Polosky, Marc A.

doi:10.1117/12.302397

Cited by 6 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Its main drawback is the inability to determine the phase relationship between measurements of different points [32]. Many monitoring schemes applied to MEMS use optical methods that provide low noise and high accuracy metrology, but these bulk optical systems are employed only during dielevel testing prior to device packaging [33]. Electrical means for sensing device motion during device operation have been explored [19], however, the dynamic range of the signal associated with device movement is small compared with the drive voltage signal.…”

Section: Integrated Through Wafer Monitoring Methodsmentioning

confidence: 99%

Modeling and real-time feedback control of MEMS device

Wang¹

View full text Add to dashboard Cite

Modeling and Real-Time Feedback Control of MEMS Device Limin Wang Applying closed-loop control to a MEMS devices not only can handle the abnormal behaviors caused by manufactory imprecision or device failure, enabling MEMS devices to survive in critical conditions, but also can increase the application where MEMS devices are used to drive components under varying load conditions. This study mainly focuses on the effort of closed-loop control on the Lateral Comb Resonator (LCR) MEMS device. The success of closed-loop control has been achieved on lateral comb resonator with novel integrated through wafer optical monitoring technique [1]. Availability of a system model and feedback signals are mandatory conditions for the implementation of closed-loop control. Because of the fabrication process tolerance, the parameters of the Lateral Comb Resonator (LCR)'s model, especially the damping parameterβ, cannot be determined accurately based merely on theoretical analysis. Therefore, performing system identification through experiments can be a tool to verify the system model. Three different system identification methods in both the time domain and frequency domain have been implemented, and the results agree. Noise analysis on the optical monitoring signal shows that at least 90% of the noise in the signal is due to the optical monitoring setup, and the simulation shows that both a wavelet thresholding method and frequency domain low pass filter are efficient in removing this Gaussian distributed noise. Different designs are developed to monitor the LCR, both for single opening and grating structure LCRs, resulting in monitoring signals that are very different in nature. The optical monitoring signal for single opening device is highly correlated with the LCR's shuttle position. After removing the noise, this signal can be used directly as a feedback signal to perform closed-loop control on the shuttle for damping shock effect or to perform stroke-length control on the shuttle [2]. The optical monitoring signal for the grating structure LCR is a kind of frequency modulation of the shuttle's displacement. Based on this signal, both position and velocity signals can be reconstructed in real time [1,3]. Even though the reconstructed position and velocity signals will inherit and even amplify all the noises that exists in the optical monitoring signal, with this method acceptable performance has been achieved in the tracking control experiment of the LCR's shuttle. In this experiment, the newly designed model reference adaptive fuzzy sliding controller (MFSC) effectively minimized the side effects caused by either signal noise or imprecision of the system model. Furthermore, experimental success on force estimation has been achieved based on this signal reconstruction method [4]. The signal reconstruction method, which can decouple the noise from the optical signal, has been implemented. 2µm's resolution can be achieved with the current single beam optical monitoring method. The resolution can be improved several times with...

show abstract

Section: Integrated Through Wafer Monitoring Methodsmentioning

confidence: 99%

Modeling and real-time feedback control of MEMS device

Wang¹

View full text Add to dashboard Cite

show abstract

“…As discussed earlier, many MEMS monitoring schemes use bulk optical methods that provide low noise and high accuracy metrology. However, these are employed only during die-level testing prior to device packaging [32]. Electrical means of sensing device motion during device operation have been explored.…”

Section: Integrated Optical Monitoring and Control Explorationmentioning

confidence: 99%

Integrated through -wafer optical monitoring of MEMS for closed -loop control

Dawson¹

View full text Add to dashboard Cite

Current trends in many microelectronic systems show an increased use of microelectromechanical systems (MEMS) to perform a variety of tasks. The increased market for MEMS has led to microsystem technologies being employed in physically demanding environments and safety critical applications. This creates the need for higher degrees of certainty in MEMS operation, especially in systems that contain drive components operating under time varying load conditions. Situations such as these give rise to the need for detailed knowledge of the operational states of MEMS over the lifetime of the device, as well as device fault detection. Accurately obtaining this information by a means decoupled from the system shows the potential to further enable both complex and simple MEMS, and allows for the application of closed-loop control. Preliminary through-wafer optical monitoring research efforts have shown that through-wafer optical probing is suitable for characterizing and measuring the behavior of lateral harmonic oscillators. This presentation will discuss research undertaken to establish integrated optical monitoring (IOM) for closed-loop control. Design of the optical microprobe setup, as well as device geometry, were completed to achieve a through-wafer optical signal with increased positional resolution and mechanical stability. Successful linear closed-loop control results achieved using the redesigned probe setup and devices will be presented. Increased displacement information in the optical output waveform is needed for the successful application of more robust, nonlinear control routines. Theoretical optical output field intensity studies are presented and compared with experimental output waveforms, showing a positional resolution of 2 µm using grating structures. Initial binary Fresnel diffractive optical microelement design layout, fabrication parameters, and testing results will be given as well for implementation of a fully integrated optical monitoring system.

show abstract