EECS Graduate Student Presents at International IEEE Conference

Jesper Eklund, a fourth-year graduate student, recently presented a paper titled, “Spherical Rubidium Vapor Cells Fabricated by Micro Glass Blowing,” at the 20th annual Institute of Electrical and Electronics Engineering International Conference on Micro-Electro-Mechanical Systems (MEMS) 2007, in Kobe, Japan. 

Eklund’s paper was one of only 43 submissions - from 611 received - selected for an oral presentation, which he gave to more than 600 conference attendees. His presentation demonstrated glass blowing on a micro-scale, which is intended to advance the development of a nuclear magnetic resonance gyroscope - a precision instrument for measuring the rotational motion of a structure or vehicle.

Conventional, but expensive, gyroscopes have been used for more than half a century in navigation systems in ships and airplanes.  Over the last two decades, interest has increased in developing smaller, low-cost gyroscopes.  Today, these micromachined gyroscopes, or microgyroscopes, are used in many consumer products, such as anti-rollover systems and stability control in cars, stabilization systems in camcorders and cameras, video game controllers, and the Segway Personal Transporter. Eklund explained that while affordable, microgyroscopes still lag behind their large counterparts in performance because they are not as sensitive, and are therefore not yet suitable for large-vessel navigation.

Together with his faculty advisor, Andrei Shkel, associate professor of mechanical and aerospace engineering and electrical engineering and computer science, as well as director of the UC Irvine MicroSystems Laboratory, Eklund is working to improve the performance of micromachined gyroscopes by developing a highly sensitive gyroscope based on nuclear magnetic resonance (NMR), the main principle behind magnetic resonance imaging, commonly know as an MRI, used in hospitals. 

NMR is a physical phenomenon in which atomic nuclei spin around the axis of a static magnetic field, creating oscillating magnetic fields and emitting a detectable amount of electromagnetic radiation.  In an NMR gyroscope, the rotation of confined gas atoms around magnetic field lines is utilized to detect the rotation of a structure or a vehicle.  It is estimated that micromachined NMR gyroscopes will be highly sensitive to rotation, making them suitable for navigation applications at a fraction of the size and cost of large, conventional gyroscopes.

A spherical gas confinement chamber for the NMR substance, consisting of an alkali vapor and noble gas isotopes, is preferred to create an extremely uniform magnetic field.  Spherical shapes, however, cannot be made using conventional micromachining techniques. In order to address this problem, Eklund and Shkel developed a wafer-level micro glass blowing process, presented at MEMS 2007, in which thousands of microscopic spherical glass parts can be shaped simultaneously. The fabrication process is based on etching cavities in silicon, followed by bonding a thin glass wafer to the etched silicon wafer. The bonded wafers are then heated inside a furnace at a temperature above the softening point of the glass, and because of the expansion of the heated, trapped gas in the cavities, the glass is blown into three-dimensional round structures.

Unlike traditional glass blowing techniques, external blowing is not required during this fabrication process. Instead, the glass spheres are automatically shaped by the increased pressure inside the sealed cavities. This enables the cost-effective fabrication of thousands of microsphereres at once.

Eklund and Shkel envision this micro glass blowing process as opening the door for a new type of three-dimensional MEMS.  In addition to the gas confinement chambers presented at the MEMS 2007 conference, the fabrication process may also be appropriate for other applications, such as a “lab on a chip,” which researchers hope will be able to diagnose and treat diseases via one simple process - using a microchip that has the capacity to combine multiple lab functions on a single, small chip.

This technology was developed as part of the Navigation-Grade Integrated Micro Gyroscope program, funded by the Defense Advanced Research Projects Agency.  The project is a collaborative effort between the MicroSystems Laboratory at UC Irvine and the Time and Frequency Division of the National Institute of Standards and Technology in Boulder, CO.

Eklund is pursuing a Ph.D. degree in electrical and computer engineering, and holds an M.S. degree in electrical and computer engineering from UC Irvine. 

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