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Researchers at Binghamton University design a more durable MEMS switch

By Rachael Flores

January 3, 2019

Researchers from the Department of Mechanical Engineering at Binghamton University have developed a way to make cell phones and power lines more durable.

Assistant Professor Sherry Towfighian and graduate student Mark Pallay created a new type of microelectromechanical system, better known as a MEMS switch, that uses electrostatic levitation to provide a more robust system.

"All cell phones use MEMS switches for wireless communication, but traditionally there are only two electrodes," Towfighian said. "These switches open and close several times for only one hour, but their current life is limited by the two-electrode system."

When the two electrodes come into contact, after several repetitions, the surface of the lower electrode is damaged, leading to a MEMS switch that must be discarded and replaced. Some researchers have tried to avoid damage by adding dimples or landing pads to the electrodes to reduce the contact area when the electrodes collide, but Towfighian explained that this only delays the rupture of the material.

I wanted to create a system that prevents damage completely. Instead of following the two-electrode model, he designed a MEMS switch with three electrodes on the bottom and one electrode parallel to the others. The two lower electrodes on the right and left side are charged, while the middle and top electrodes are grounded.

"This type of MEMS switch is normally closed, but the side electrodes provide a strong upward force that can overcome the forces between the two central electrodes and open the switch," Towfighian explained. This force, called electrostatic levitation, is currently not available with the two-electrode system. The ability to generate this force prevents permanent device damage after continuous use and allows a reliable bi-directional switch.

"For cell phones, this design means a longer life and fewer component replacements," Towfighian said. "For power lines, this type of MEMS switch would be useful when the voltage exceeds a limit and we want to open the switch. The design allows us to have more reliable switches to monitor unusual spikes in voltage, such as those caused by an earthquake, that can cause public safety hazards. "

The study entitled" A MEMS switch that is reliable uses electrostatic levitation "was published on November 20, 2018, in Applied Physics Letters and was funded by the Division of Electrical, Communications and Cyberspace Systems (ECCS) of the National Science Foundation (ECCS), for its acronyms in English) # 1608692.

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