Standards Development

Scope

This part of IEC 63203-204-X specifies a method of evaluating energy harvesting performance of fabric based piezoelectric nanogenerator for wearable electronic devices. This standard is applicable to analyse the power generator performance under stretching, tapping and bending mode

Purpose

Energy harvesting from different mechanical energy sources is gaining lot of interest in the field of wearableelectronics. Harvesting energy from piezoelectric textiles is gaining ground because of its flexibility, ease of processing and ability to provide sufficient voltage directly. They may also be used for energy storage and self-powered electronic applications.

Different existing IEC standards (IEC 62830-1:2017, IEC 62830-4:2019) described vibration based piezoelectric devices and device evaluation by vibration method. The evaluation of properties was performed on continuous and isotropic polymers (films) with sputtered electrodes and further encapsulation in flexible substrate like PDMS/PEI. The performance of the energy harvester was tested by vibration exciter. Another IEC standard (IEC 62969-3:2018) described shock driven piezoelectric device for sensing applications in automotives.

External stimuli like vibration and shock may fail in utilizing maximum output from anisotropic textile fabrics which are highly flexible and porous in nature (unlike continuous films). Further, continuous electrode designs (like sputter coating) cannot be applied on piezoelectric textiles as they may result in contact shorting. Textile materials are inherently flexible and can be twisted, bent or stretched and hence needs no external substrate to induce these motions into it.

Therefore, in order to fulfil the existing gaps in the existing standards, stretching, tapping and bending modes are chosen as the most appropriate stimuli for harvesting energy from piezoelectric textiles. By these methods, the dipoles in the piezoelectric fabric will experience strain along stretching, tapping or bending directions and generate higher energy. This is unlike highly probable event of diminishing dipole charges in vibration mode. Electrode materials and design play an important role in higher energy outputs. Conductive materials as filament or fabric can be used as an electrode for harvesting charges f rom piezoelectric fabric. These electrode systems will sandwich piezoelectric fabric of interest and prevent contact shorting.

In the view of above scenario, it is important to standardize the measurement parameters and testing conditions for evaluating the performance of piezoelectric fabric structure, which will be an impetus in the field of wearable electronics.