2019-056 – Manufacturing MEMS Resonators with Tunable Frequency

Background With the growing demand for Cyber Physical Systems (CPS) and Internet of Things (IoT) applications, there is an increasing desire to have self-sustaining systems. Current technology requires these systems to be powered by batteries; however, batteries need to be replaced. This can be an expensive and labor-intensive process, especially if the CPS or IoT system is in a remote location. Therefore, there is a desire to have a device capable of harvesting energy from the ambient environment that will allow the system to be self-sustaining and not rely on batteries for power. Vibrational energy harvesting is often the desired mechanism used over other energy harvesting methods, due to the availability of a constantly operating vibration source, unlike solar energy which requires light. MEMS energy harvesters are typically desired over bulk devices because the energy harvester system should be similar in size to the battery it is replacing. It is estimated that in the near future there will be billions or even trillions of IoT worldwide which will need power. Applications include structural health monitoring, sensors for drones, automotive, and military. Each application requires a device that resonates at a specific frequency, leading each industry to custom manufacture the devices. For energy harvesting applications, frequencies between 50 to 200 Hz are typically required. To achieve these frequencies the cantilever is controlled by its dimensions, material properties, and mass. However, due to the custom dimensions and materials, mass-production of these devices is not cost effective. These custom devices have struggled with commercialization, leading to the need for an innovative fabrication method to develop a manufacturing method to mass-produce a universal device capable of customization in the final stage. Technology Description A researcher at the University of New Mexico has developed a method of tuning the resonant frequency of a MEMS energy harvester that is compatible with standard MEMS fabrication techniques. This invention allows manufacturers the ability to make a universal device so they can batch fabricate large quantities of devices and then fine-tune it in the last step of the fabrication process to meet customer demands. Tuning methods developed involve manufacturing methods of embedding mass into the cantilever structure during the final fabrication stage. By varying the embedded mass and its location on the cantilever the resonant frequency can be tuned for a wide range of frequencies with high resolution. This method will further enhance the Technology Readiness Levels (TRLs) of MEMS based vibrational energy harvesters to power CPS and IoT applications, enabling insight into the development of batch fabrication of these devices. The process reduces production costs and labor output. Andrew Roerick aroerick@innovations.unm.edu 505-277-0608