Reactive ion etching of poly(vinylidene fluoride-trifluoroethylene) copolymer for flexible piezoelectric devices

Abstract

A microfabrication process for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) based flexible piezoelectric devices is proposed using heat controlled spin coating and reactive ion etching (RIE) techniques. Dry etching of P(VDF-TrFE) in CF 4 +O 2 plasma is found to be more effective than that using SF 6 +O 2 or Ar+O 2 feed gas with the same radiofrequency power and pressure conditions. A maximum etching rate of 400 nm/min is obtained using the CF 4 +O 2 plasma with an oxygen concentration of 60% at , and heart beat sensors [7]. Cantilever shaped P(VDF-TrFE) actuators were also fabricated for mini-robots application, in which a multilayered P(VDF-TrFE) structure was proposed to achieve a large displacement with a low driving voltage [8]. Most of the PVDF based devices were fabricated using commercial PVDF films and traditional fabrication techniques such as scissoring, laser machining, and lamination [9,10]. With the aim of integrating piezoelectric polymers into microdevices, ionized evaporation, electrospray, electrospun, Langmuir-Blodgett deposition, and heat controlled spin coating methods were developed. Ionized evaporation and electrospray processes were reported to deposit PVDF films for pyroelectric infrared sensors in 1990s [11,12]. An electrospun method was employed to fabricate PVDF nanofibers for sensors and energy harvesters [5,13]. For fabrication of nonvolatile memory devices, low-temperature fabrication approaches including Langmuir-Blodgett deposition [14,15] and spin coating methods [16] were developed. The spin coated P(VDF-TrFE) films, intrinsically tending to form phase I crystal with a high remanent polarization, are

Aligned P(VDF-TrFE) Nanofibers for Enhanced Piezoelectric Directional Strain Sensing

“…Compared with spin-coated P(VDF-TrFE) films, which require additional electrical poling to achieve high piezoelectricity [ 40 ], the P(VDF-TrFE) nanofibers are advantageous for excellent response without annealing. As shown in Figures 3c and 5f, the annealing process significantly enhanced the piezoelectric response, which was verified by previous studies for both PVDF and P(VDF-TrFE) [ 41 , 42 , 43 ]. Directional sensing is universal in biological sensory organs such as hair cells in the inner ear, lateral line neuromasts of fish, and mechanosensitive hair sensilla of insects [ 44 , 45 , 46 ].…”

Spin Coating and Micro-Patterning Optimization of Composite Thin Films Based on PVDF

“…This technique was recently reported for etching PVDF thin films. Miki et al [49] and Jiang et al [54] experimented different gas mixture and etching conditions, on which we based our RIE process. Fluorine chemistry plasma (CHF 3 ) with a flow rate of 48 sccm was perfectly adapted in our case.…”

Development of a Flexible Artificial Lateral Line Canal System for Hydrodynamic Pressure Detection

“…Prior studies have confirmed that IPMC can respond to static displacement and are sensitive to flow rate when used in ALL systems [ 18 , 19 ]. Polyvinylidene fluoride (PVDF) is a piezoelectric polymer that offers high piezoelectric voltage constants and is widely used in microelectromechanical systems [ 20 , 21 ]. In our proposed ALL canal system, PVDF was used in the cantilevered flow-sensing elements, and PDMS was used as the material for the canals.…”