Person:

Guder, Firat

This paper describes the design and fabrication of electrically controlled paper actuators that operate based on the dimensional changes that occur in paper when the moisture absorbed on the surface of the cellulose fibers changes. These actuators are called “Hygroexpansive Electrothermal Paper Actuators” (HEPAs). The actuators are made from paper, conducting polymer, and adhesive tape. They are lightweight, inexpensive, and can be fabricated using simple printing techniques. The central element of the HEPAs is a porous conducting path (used to provide electrothermal heating) that changes the moisture content of the paper and causes actuation. This conducting path is made by embedding a conducting polymer (PEDOT:PSS) within the paper, and thus making a paper/polymer composite that retains the porosity and hydrophilicity of paper. Different types of HEPAs (straight, precurved, and creased) achieved different types of motions (e.g., bending motion, accordion type motion). A theoretical model for their behavior is proposed. These actuators have been used for the manipulation of liquids and for the fabrication of an optical shutter.

The fields of paper microfluidics and printed electronics have developed independently, and are incompatible in many of their aspects (e.g. printed electronic thin films are not designed to tolerate the flows of liquids, and especially of water, nor are water filled-channels designed to conduct electrons). This work demonstrates monolithic integration of microfluidics and electronics on paper, by extending the use of paper microfluidics to the fabrication of electrical conductors by the wicking of aqueous conducting inks inside microfluidic channels. These conductors are unique in that they can act as wires, electrodes, and microfluidic channels at the same time. These techniques, make it possible to print both two- and three-dimensional fluidic, electrofluidic, and electrical components using simple methods, and thus to design new paper devices. This paper demonstrates the fabrication of three classes of devices: i) 3D paper “printed circuit boards”, ii) vertical-flow electroanalytical devices, and iii) foldable, all-organic paper batteries.