Virtual Button® Micro Electro Mechanical System Accelerometer Design

David Effa, Andrew Zwart, and Myung Sik Kim
Case revision date: 
3 pages (case study)

Virtual Button® technology has been developed by VBT Innovations Inc. a high tech company located and established in Waterloo, Ontario, Canada in 2008. Virtual Buttons® are meant to augment or replace mechanical buttons and capacitive touch screens on consumer electronics devices such as cell phones. This technology enables buttons to be placed on flat and curved surfaces, edges, and locations where a mechanical button is not feasible. Figure 1 shows an example of a Virtual Button® application for a cell phone tapping user interface. Virtual Button® offers multiple advantages as it can endure harsh environments with high level of shock, vibration, and humidity. It can be also suitable for sensitive environments as the technology enables buttons to be placed on any existing surface, offering design flexibility. Since there is no direct connection between the sensor inside the device and its exterior; the Virtual Buttons® is safe for steam chambers and ethylene oxide cleaning as well. One of the enabling technologies of this system is the Micro Electro Mechanical System (MEMS) accelerometer. This accelerometer must be designed and fabricated to meet the special requirements of VBT Innovations Inc.

phone showing Any location can be a button using virtual button technology

Any location can be a button using virtual button technology

Learning objectives: 

This case study is intended to have students exposed to MEMS and allow students to design a fabrication method using PolyMUMPs for a MEMS device with already optimized device geometry and provided device performance requirements and fabrication constraints. At the end of this case study, students will be able to discuss the concept of MEMS devices and fabrication processes, and generate a MEMS mask (layout) for a given fabrication process.

Key words: 
Micro Electro Mechanical System (MEMS); Fabrication processes; PolyMUMPs
CEAB attributes: 
Module 01 – Case Study
Module 02 – Virtual Button® MEMS Accelerometer Fabrication using PolyMUMPs®
Module TN – Teaching Note

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