PE-based Piezoelectric Film Cost-effective Alternative to PVDF

A novel piezoelectric film made from polyethylene (PE) reportedly combines mechanical flexibility with a very high piezoelectric response. In fact, it reportedly doubles the properties of commercially available piezoelectric polymers, such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). The film developed by researchers at Sabic is described as a cost-effective alternative to PVDF in high-end applications.

Alternative to brittle ceramics and inadequate piezoelectric polymers.

Piezoelectric materials generate an electrical signal in response to mechanical stress. The advent of the internet of things (IoT) and artificial intelligence (AI) has increased demand for self-powered flexible sensing devices, according to Sabic, which require flexible piezoelectric film to function.

However, commercially available inorganic piezoelectric ceramics are heavy and brittle. Moreover, the manufacturing process is complex, since elevated temperatures are required to achieve the desired piezoelectric performance. The materials also need to be produced in thin layers on a plastic substrate for integration with a flexible device, and there are limited options of high-temperature-resistant, flexible plastic substrates.

Commercial piezoelectric polymers can be an alternative to piezoceramics, but applications also are limited because of their low piezoelectric properties.

Lead-free piezoceramics are integrated in the PE-based flexible film. Image courtesy of Sabic.

The piezoelectric film designed and developed by Sabic is said to offer several advantages that address the unmet needs of flexible sensing devices, including:

Getting the lead out.

The best performing piezoelectric materials to date have been based on lead, a toxic material that is heavily regulated in the European Union through the Restriction of Hazardous Substances (RoHS) Directive, for example. By contrast, Sabic claims that its proprietary piezoelectric solution does not contain lead or any other toxic chemicals. The composite comprises PE and a proprietary lead-free ceramic, and Sabic said it has developed unique design and fabrication expertise that allows its researchers to tune the chemical composition and morphology of the ceramic. With its extensive portfolio of resins, Sabic can customize the piezoelectric composition to meet the requirements of specific applications.

For example, the piezoelectric film’s capability of generating electrical signals in response to different force levels and motion combined with the material’s conformability make it suitable for wearable sensor applications that monitor heart rates and breathing.

The film’s low resistance to sound waves make possible applications in acoustic sensors and medical imaging.

Step change in smart shoes.

The film also generates voltage in proximity to objects, which can be applied in proximity sensors.

The inherent characteristics of the material, including resilience, compression set, and creep properties, open opportunities in smart shoe soles for gait recognition, fall detection, and fitness tracking.  

The film’s energy-harvesting capability also creates opportunities in self-powered sensing devices, possibly eliminating the need for batteries, said Sabic.

The PE piezoelectric film technology was developed in a collaborative project involving Sabic, the Technical University of Delft and the Holst Center in the Netherlands, and Penn State University in the United States.