Ionic conductive ink and stretchable touch sensors or panels based on the ionic conductive ink

#This application is a national phase entry of PCT/SG2019/050380, filed on 30 Jul. 2019, which claims the benefit of priority of Singapore Patent Application No. 10201806483Y, filed 30 Jul. 2018, the contents of which are hereby incorporated by reference in their entirety for all purposes.

#The present disclosure relates to an ionic conductive ink for use in touch sensor panels. The present disclosure also relates to a method of producing the ionic conductive ink.

#The development and maturing of touch sensing technology has enabled simple and intuitive real-time human-machine interaction and communication. Just as human's skin may perceive tactile feeling, state-of-the-art touch sensors may be built to detect every single, multi-point or gestural touch input and transfer these signals to a controller for post-processing.

#The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present disclosure are described with reference to the following drawings, in which:

#FIG. 1A shows a photo of an ionic conductive ink, which is a polyvinyl alcohol (PVA) based ionic conductive ink prepared using a mixture of solvents that includes water and dimethyl sulfoxide (DMSO).

#FIG. 1B shows a plot of dynamic viscosity of the ionic conductive ink measured at a constant shear rate of 100 s−1.

#The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practised. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

#Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

#In the present disclosure, an ionic conductive gel may be patterned into electrodes via drop-on-demand (DOD) inkjet printing of an ionic conductive ink. When the ionic conductive ink dries and gels, the ionic conductive gel may be formed. The term “inkjet printing” and grammatical variants thereof used herein refers to a form of printing that involves recreation of a digital image from a computer as an example by propelling droplets of ink onto a substrate. The term “DOD” refers to a form of inkjet printing that either involves heat or a piezoelectric material to generate individual ink droplets then deposit them at desired locations on a substrate. For example, in thermal DOD inkjet printing, a pulse of current may be passed through a heating element that causes rapid vaporization of ink stored in a chamber to form a bubble, and the bubble causes a large pressure increase, thereby propelling a droplet of ink onto a substrate. In piezoelectric DOD inkjet printing, a voltage may be applied to cause the piezoelectric material to change its shape to generate a pressure pulse in the ink fluid stored in the chamber, which forces a droplet of ink from the nozzle onto a substrate.