Laura S. Marshall
SAN FRANCISCO, Jan. 26, 2010 – Various applications of microelectromechanical and micro-optoelectromechanical systems (MEMS and MOEMS, respectively) proved popular at the MOEMS-MEMS subconference’s plenary talks Monday morning at SPIE’s Photonics West.
The talks were nearly all full, with several attendees forced to stand at the back or along the sides of the room, but that didn’t appear to deter anyone from joining the crowd to hear about the latest developments in MEMS technologies.
MEMS for sensing
In “Emerging Research in Microsystems: Opportunities and Challenges in Health-Care and Environmental Sensing Applications,” Yogesh B. Gianchandani of the University of Michigan in Ann Arbor and the National Science Foundation's Engineering Research Center for Wireless Integrated MicroSystems, discussed the challenges that face researchers who are exploring ways to apply MEMS in these areas.
Some of the specific environmental applications Gianchandani mentioned were infrastructure monitoring, energy and power, and gas analysis. He outlined challenges for 2015, which include developing sensors to monitor air, water and food; creating new ways to harvest and store energy; and finding lower-cost methods of sensor manufacturing. By 2040, he said, the challenges will include finding extremely remote sensors, and developing cyber-physical systems and seamlessly integrating sensors into existing infrastructure. On the health care side, he talked about neuroimplants, active stents and drug delivery systems.
At the end of his talk, Gianchandani outlined some generalizations about MEMS engineering – and engineering itself. Interdisciplinary research, he said, must be placed in the context of engineered systems in order to be most practical. He also pointed out that industry-university partnerships can perform ground-breaking work, adding that education programs are needed to advance the field, and that industry-university partnerships can play important roles in this advancement.
For “MEMS Technologies for Artificial Retinas,” Wilfried Mokwa of Aachen University in Germany delivered an engaging talk about research into incorporating MEMS technologies into devices to restore sight to people blinded by retinal degeneration.
As electrical stimulation of the retinal ganglion cells has been shown to yield visual sensations, Mokwa explained, there are a few different approaches. In the subretinal approach, the degenerated photoreceptors are replaced by a stimulation electrode array. In the epiretinal approach, a stimulation electrode array is placed on the inner retina to stimulate the ganglion cells. All previously developed systems rely on external devices connected to implanted components.
But the Epiret 3 system, developed by German researchers whose goal was “to put the whole implant into the eye” – that is, to create a system that needs no external devices to function. Removing the need for a cable connection to the eye cuts down the risk of infection, he said.
Test results in six patients have been extraordinarily promising, Mokwa reported: All six systems worked in the tests; all six patients responded to bright stimuli (spots, points, lines).
In “Shaping Light: MOEMS Deformable Mirrors for Microscopes and Telescopes,” Thomas Bifano of Boston University’s Photonics Center and Boston Micromachines Corp. described his work at the university and his company to design and fabricate MOEMS deformable mirrors (DMs) for adaptive optics (AO) applications including large-telescope astronomy and retinal imaging.
MEMS just makes sense for DMs, Bifano said. They’re easy to scale to larger arrays; they’re small in size, weight and power requirements; their manufacturing costs are relatively low; and they can be batch-produced.
And they offer significant improvements in resolution and contrast, as he showed using examples from some large ground-based telescopes. The example images showed how MEMS technology has allowed these instruments to overcome challenges from wavefront aberrations due to atmospheric conditions.
Laura S. Marshall
- adaptive optics
- Optical components or assemblies whose performance is monitored and controlled so as to compensate for aberrations, static or dynamic perturbations such as thermal, mechanical and acoustical disturbances, or to adapt to changing conditions, needs or missions. The most familiar example is the "rubber mirror,'' whose surface shape, and thus reflective qualities, can be controlled by electromechanical means. See also active optics; phase conjugation.
- With respect to a lens, the reciprocal of its focal length. The term power, as applied to a telescope or microscope, often is used as an abbreviation for magnifying power.
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