A Flexoelectric Micro-Accelerometer

In this paper new acceleration sensors using flexoelectric barium strontium titanate (BST) were designed, fabricated and tested for vibration monitoring. The flexoelectric sensors were configured as rectangular and trapezoidal cross-section micro-unimorphs with a BST layer bonded onto a Si substrate. Proof masses were attached to unimorph tips to amplify the transverse flexoelectric responses of the BST layers. The theoretical model was developed and validated by vibration tests using the prototyped flexoelectric micro-unimorphs. The prototyped accelerometer showed a stable sensitivity of 0.84 pC/g in the frequency range of 100 Hz ∼ 1.6 kHz, which agreed well with the analytical results. The aging property of the flexoelectric sensor was demonstrated to be much better than that of the reported piezoelectric materials right after poling. Scaling effect analysis was performed for flexoelectric unimorphs. The test results and initial scaling effect analysis indicate that micro/nano flexoelectric sensing hold promise for a broad range of applications.