Fabrication of Ferroelectric PVDF:TrFE Foil via Controlled Dewetting

Description

Flexible electronics and sensor technologies are becoming increasingly important due to their wide-ranging
applications in wearable devices, healthcare monitoring, environmental sensing, and industrial automation [1].
Especially poly(vinylidene-fluoride) (PVDF) and its copolymer with trifluoroethylene have been some of the
most used polymers in force-sensing applications due to their strong piezoelectricity and wide range of ways
of fabrication [2]. Usually, force sensors using PVDF are fabricated either by using a prefabricated and
polarized large-scale foil, which is cut to size, creating fibers to embed into a polymer matrix or similar, or by
printing the sensor and its electrodes directly onto the final substrate [3,4].
This work presents an alternative method for fabricating Poly(vinylidene fluoride–trifluoroethylene)
(PVDF:TrFE) foils of arbitrary shape, size, and thickness via stencil printing and following controlled
dewetting from the substrate. This foil could be used to fabricate various kinds of devices utilizing the chemical
stability of PVDF, or flexible piezoelectric or ferroelectric sensors. Compared to utilizing a prefabricated foil,
this approach does not require cutting the foil before the following steps or fixing it for any printing process.
Subsequent printing of other functional materials allows for the fabrication of sensors on this fixed substrate
to any shape and design desired. After all the printing steps are performed, the foil can be separated via
dewetting, leaving the self-supported sensors ready for use.
The proposed process starts with stencil printing a layer of PVDF:TrFE onto a gold substrate. This step is
identical to existing fabrication processes for rigid PVDF-based force sensors [5]. The substrate used is a
printed circuit board (PCB) with a single large electrode coated with electroless nickel immersion gold (ENIG)
as shown in Figure 1. Afterward, other necessary processing steps may be conducted to build the finished
device, which is still attached to the rigid substrate. An additional layer of PVDF:TrFE may be needed for
passivation and protection from the chemicals used in the following steps. After these steps, a solution of
acetone and gamma-butyrolactone (GBL) in a mixture of approximately 50:50 is applied to simultaneously
soften the PVDF:TrFE layer and cause the first layer to dewet from the gold substrate. It is crucial to only add
as little as necessary, as the PVDF:TrFE might get partially dissolved. Successful dewetting can be observed
via a honeycomb-like structure appearing due to the detachment and slight expansion of the first PVDF:TrFE
layer. The foil can then be cut free from any attachments (e.g., parts of the substrate that are not covered in
ENIG) and then dried off in warm air.
This work has been partially supported by the State of Upper Austria in the frame of the Center for
Symbiotic Mechatronics (of the Linz Center of Mechatronics, LCM).

Period	16 Sept 2025
Event title	51st International Micro and Nano Engineering Conference
Event type	Conference
Location	Southampton, United KingdomShow on map
Degree of Recognition	International