Additive Manufacturing of Conformable Electronics on Complex Objects Through Combined Use of Liquid Metal Ink and Packaging Material

Abstract

Conventional electronics manufacturing strategies are generally complicated, time, water, material and energy consuming. Besides, building an electronic device on a complex object generally requests a series of different connecting wires which would make the machine in a mess. Here from an alternative approach, we proposed an innovative method of realizing conformable electronic connection by the low melting point metal ink and the related flexible packaging material for quickly manufacturing electronics. The liquid metal ink could easily and directly be written on a series of complex surfaces and then coated with the packaging material which is to offer mechanical strength and prevent it from air oxygenization. For illustrating purpose, an electrical connection of LED circuit on cylindrical surface, concave, inclined structure, planes of right angle and sphere was demonstrated. Such optoelectronic device appears rather compact without any evident connecting wires exposing out. Further, a thermal cycle experiment (−40°C∼120°C) was designed to test the variation of the electrical properties of the working sample. It is disclosed that the conductive line covered by the packaging material has a temperature coefficient of 0.255 mΩ/°C (T0 = −16°C) and finally an increasing rate of only 4.24% in resistance after all thermal aging cycles. This electrical connection method is expected to have a significant impact in surface mount technology. Its applications will not only in industry but also can change the way we interact with each other and our everyday life.