Extreme angle, tip-tilt MEMS micromirror enabling full hemispheric, quasi-static optical coverage

Pollock, Corey; Javor, Josh; Stange, Alexander; Barrett, Lawrence; Bishop, David J.

doi:10.1364/oe.27.015318

Cited by 19 publications

(15 citation statements)

References 21 publications

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“…These feedforward control algorithms enable ideal scanner and galvo motion, even with PWM control. Such an approach is appropriate for our MEMS micromirror with full hemispheric coverage [7] and for our five degrees-of-freedom scanner [6], as it supplements unique device design with practical control methods. We also build off other practical control discoveries, such as how to improve step-and-settle times using PWM [16] and how to perform analog control of MEMS devices [17], although the latter technique does not use the natural frequency of the device.…”

Section: Discussionmentioning

confidence: 99%

Feedforward Control Algorithms for MEMS Galvos and Scanners

Barrett

Imboden²,

Javor

et al. 2021

J. Microelectromech. Syst.

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Optical systems typically use galvanometers (galvos) and scanners. Galvos move, quasi-statically, from one static position to another. Scanners move in an oscillatory fashion, typically at the device resonant frequency. MEMS devices, which have many advantages and are often used in optical systems, are typically high Q devices. Moving from one position to another for a galvo or one amplitude to another for scanners, can take many periods to settle following the ring down. During these transitions, the optical system is inactive. Here, we show how precisely timed pulses can be used (in an open loop manner) to begin or end scanner motion without ring up/ring down time. The size of pulse required is found to depend on the Q of the device, and relationships are derived. The pulse can also be separated into multiple pulse spaced one period apart if pulses of the necessary size are not possible due to constraints of the physical device. For finite Q scanners, the amplitude decreases after the initial pulse due to damping. This can be eliminated by applying an excitation at the frequency of the scanner. The necessary amplitude for this excitation is derived. Finally, by combining this open loop control algorithm with an open loop control algorithm for galvo motion the device can seamlessly move between scanner and galvo functioning. These control algorithms are demonstrated using computer simulations, analytical models and a commercially available MEMS mirror (Mirrorcle Technologies, A8L2.2).[2020-0238]

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Section: Discussionmentioning

confidence: 99%

Feedforward Control Algorithms for MEMS Galvos and Scanners

Barrett

Imboden²,

Javor

et al. 2021

J. Microelectromech. Syst.

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“…A permanent magnet distorts the SEM image; thus, the device shown is for illustrative purposes only, where the magnet is completely demagnetized and the UV glue under the spheres overlaps some portions of the spring (compromising the sensing ability). Similar fabrication techniques have been used to develop an MEMS Casimir force metrology platform 32 , a full hemisphere, tip-tilt micromirror 33 , and other MEMSs at Nokia 34 . Figure 2f shows a sensor fabricated within a custom printed circuit board (PCB) coil for gradient field characterization.…”

Section: Gradiometer Fabrication From Mems Accelerometermentioning

confidence: 99%

100 pT/cm single-point MEMS magnetic gradiometer from a commercial accelerometer

et al. 2020

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Magnetic sensing is present in our everyday interactions with consumer electronics and demonstrates the potential for the measurement of extremely weak biomagnetic fields, such as those of the heart and brain. In this work, we leverage the many benefits of microelectromechanical system (MEMS) devices to fabricate a small, low-power, and inexpensive sensor whose resolution is in the range of biomagnetic fields. At present, biomagnetic fields are measured only by expensive mechanisms such as optical pumping and superconducting quantum interference devices (SQUIDs), suggesting a large opportunity for MEMS technology in this work. The prototype fabrication is achieved by assembling micro-objects, including a permanent micromagnet, onto a postrelease commercial MEMS accelerometer using a pick-and-place technique. With this system, we demonstrate a room-temperature MEMS magnetic gradiometer. In air, the sensor's response is linear, with a resolution of 1.1 nT cm −1 , spans over 3 decades of dynamic range to 4.6 µT cm −1 , and is capable of off-resonance measurements at low frequencies. In a 1 mTorr vacuum with 20 dB magnetic shielding, the sensor achieves a 100 pT cm −1 resolution at resonance. This resolution represents a 30-fold improvement compared with that of MEMS magnetometer technology and a 1000-fold improvement compared with that of MEMS gradiometer technology. The sensor is capable of a small spatial resolution with a magnetic sensing element of 0.25 mm along its sensitive axis, a >4-fold improvement compared with that of MEMS gradiometer technology. The calculated noise floor of this platform is 110 fT cm −1 Hz −1/2 , and thus, these devices hold promise for both magnetocardiography (MCG) and magnetoencephalography (MEG) applications.

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“…The rise time and decay time on the square wave are not limited by the hall sensor (decay time of 750 μs [19]) but are instead limited by overdamped actuation from the electromagnetic coils. Open-loop drive techniques have been developed based on previous work [20], [21] to improve settling by over an order of magnitude and are demonstrated later ( Fig. 6b and c).…”

Section: Calibration Using Benchtop Microscopementioning

confidence: 99%

“…4 b-d). This system was previously developed for higher resolution fabrication on post-release silicon micro devices [21], [24], [25]. Probe station micropositioners (Cascade Microtech), coupled with glass micropipettes, are used for microscale fabrication.…”

Section: Magnetic Functionalization and Tissue Culturementioning

confidence: 99%

See 1 more Smart Citation

A Microtissue Platform to Simultaneously Actuate and Detect Mechanical Forces via Non-Contact Magnetic Approach

Javor¹,

Sundaram²,

Chen³

et al. 2020

Preprint

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Mechanical control is essential for adaptive regulation in biological systems. This work presents a magnetic, non-contact approach to simultaneous detection and actuation in a microscale tissue testbed. The platform builds upon previously developed passive mechanical platforms, where tissues self-assemble on flexible pillars. Standard detection is typically derived from microscope images and actuation is often conducted using invasive approaches. In the presented platform, actuation and detection, both derived from magnetic fields, are demonstrated with high spatial, temporal, and force resolution resulting in a detectable 0.6 µm step-size in air. The forced deflection range is +/-125 microns (+/-10% strain), and an arbitrary magnitude step-and-settle actuation is achieved in less than 1 ms. Engineered human cardiac microtissue is used to demonstrate the capabilities of the system, as cardiac tissues generate contractions and adapt to external forces. Spontaneous contractions are monitored for an hour by a built-in sensor with a signal-to-noise of 2. Cyclic actuation at 1 Hz using a 1 mT/mm magnetic field is demonstrated, where max tissue strain is 0.3%. All this is achieved in a moderate-throughput, compact device, which is easily integrated into the typical flow of biological experimentation. Simultaneous control of actuation and detection enables decisions to be made on a sample-specific basis, and in future developments, will enable arbitrary design of the mechanical environment for 3D tissue conditioning, maturation, and control.

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Extreme angle, tip-tilt MEMS micromirror enabling full hemispheric, quasi-static optical coverage

Cited by 19 publications

References 21 publications

Feedforward Control Algorithms for MEMS Galvos and Scanners

Feedforward Control Algorithms for MEMS Galvos and Scanners

100 pT/cm single-point MEMS magnetic gradiometer from a commercial accelerometer

A Microtissue Platform to Simultaneously Actuate and Detect Mechanical Forces via Non-Contact Magnetic Approach

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