Tuning an IoT MEMS Switch

Menlo Microsystems, a startup from GE, is making a MEMS-based switch fit into a broad array of systems related to Internet of Things (IoT). Already incorporated into medical systems of GE, they can tune the chip to act as a relay and power actuator for several types of industrial IoT uses, including using it as an RF switch suitable for mobile systems.

Menlo first described their electrostatic switch in 2014. They have designed it with unique metal alloys deposited on a substrate of glass. The arrangement creates a beam that a gate can pull down, making it complete a contact and allow current to flow. Compared to a solid-state switch, this electrostatic switch requires significantly less power to activate and to keep it on. This single proprietary process creates products for several vertical markets.

The low power consumption of the device allows it to handle high currents and power switching. Unlike traditional switches, the MEMS switch does not generate heat, and therefore does not require large, expensive heat sinks to keep cool.

Currently, a tiny research fab run by GE is making the switch. Menlo expects to produce it in larger quantities in mid-2018, through Silex Microsystems, a commercial fab in Sweden. According to Russ Garcia, CEO of Menlo, their biggest challenge is to get the technology qualified in a fab producing commercial items.

The device has huge opportunities as it can replace a wide variety of electromechanical and electromagnetic power switches and solid-state relays. Menlo is planning to roll out several varieties of reference boards incorporating its MEMS chips, which will be helpful in home and building automation, robotics, and industrial automation.

For instance, IoT devices such as the smart thermostat from Nest face an issue of efficiently turning on or off high power systems such as HVACs. According to Garcia, the Menlo switch can do this while drawing almost zero current. Additionally, the Menlo switch offers a two-order reduction in the size of power switches and their power consumption.

It took a 12-year research effort by GE to incubate the design of the MEMS switches. They discovered that reliability issues were related to materials MEMS used, and overcame the issues with alternate unique metal alloys for the beams and contacts of the switch including generating a novel glass substrate. This combination allows billions of on/off switches to handle kilowatts of power reliably.

The medical division of GE will be among the first users of the chip. They will use the chip to replace a complex array of pin diodes in their MRI systems. This replacement by MEMS switches can knock off $10,000 from the cost of each MRI system. This includes the payment to five PhDs who presently tune each of the machines with pin diodes. The new MEMS switch will allow an automatic programming of the system.

Although GE will be an exclusive user for the chips in their MRI systems, Menlo is discussing future uses of the chip with other MRI makers as well. According to Garcia, GE wants to create a new strategic component supplier for the chips. Menlo is also planning to use the chips for RF switches.