Fig. 2

Effects of material and structure on the device performance. a Frequency response data for the devices with different material, structure, and number of diaphragms. The zero decibel line corresponds to a response of 1 V g⁻¹. Optical microscope images (Scale bars: 100 μm) and cross-sectional schematic drawings of diaphragms are shown in the right. b The schematic shows the cross-sectional structure of a diaphragm with air holes and its structural parameters. c Effects of diaphragm diameter; diaphragm thickness; support thickness; and the number of diaphragms on the vibrational sensitivity. For each graph, low tan δ polymer was used for the diaphragm material, air holes were patterned on the diaphragm, and the structural parameters were fixed as follows unless specified: diaphragm diameter of 400 μm, diaphragm thickness of 400 nm, support thickness of 1.2 μm and an array of 25 diaphragms. The error bars represent the s.d. of the sensitivity values for the measured frequencies. d, e Microscope image (Scale bar: 2 mm) (d) and output data (e) of an optimized device: an array of 400 low tan δ polymer diaphragms with air holes on 2 cm² area