Inkjet Printed Flexible Capacitors on Textiles

Textile capacitor is an essential part of next generation wearable application. However, the flexibility of the capacitor is a big challenge for the textile products. Besides, the high dielectric constant is another block for the application of the capacitors. We fabricate a new method to form the flexible capacitor by inkjet printing. The capacitor apply the heat curable silver ink and UV curable dielectric ink which contains acrylates and urethane monomers. In order to increase the dielectric constant of the dielectric layer, a high-dielectric-constant material Barium Titanate nanoparticles (BT NPs) with an average size of 200 nm is embedded in the dielectric layer. The tetragonal phase BT NPs can increase the dielectric constant and reduce the dielectric loss especially at high frequency. First, we inkjet printing the silver ink on the woven fabric. Then we use the dielectric ink to form the film to block the silver ink. Then we use the dielectric ink and BT NPs to form the dielectric layer and use the dielectric ink polymerization under UV light to combine the two conductive layers together to form a flexible capacitor. This capacitor can be designed by inkjet printing with high resolution and different shapes to satisfy the needs of textile products and in other areas as well. After printing we test the dielectric properties and capacitance, then observe the sandwich structure of the capacitor by cross-sectional film from SEM images. This capacitor show flexibility like original textiles and can be easily applied in the cloth which can be a promising application in charge-storage.