Paper Electronics

The concentration of free chlorine used for disinfecting drinking water, recreational water, and food processing water is critical for environmental and human health conditions, and should be controlled within stipulated ranges. This report, for the first time, describes a paper-based electrochemical free chlorine sensor fabricated by hand-drawing. The electrical resistivity of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) chemoresistor increases when it is exposed to free chlorine in water due to oxidation reactions. Because the relative change of the electrical resistance represents the sensor’s response, the sensor can be fabricated by hand-drawing with different shapes and dimensions. The fabrication steps are all at room temperature, require no instrumentation or equipment, and can be carried out by untrained personnel. The fabricated sensor is mechanically stable, reusable, has a wide sensing range, and can accurately measure free chlorine concentrations in real water samples. Therefore, the low-cost, hand-drawn free chlorine sensor is of great significance for water quality monitoring in less developed areas where fabrication facilities, analytical equipment, and trained personnel are limited, but the need for analytical devices is critical. In addition to the free chlorine sensor demonstrated in this study, other types of PEDOT:PSS-based sensors and electronic devices can be fabricated by the developed hand-drawing process.

With the rise of electrophoretic-display media from several sources, the world is opening up for new uses of electronic displays. Where "immersive reading" used to be a task strictly reserved for paper, displays can now fulfill that role. Many challenges still remain, such as full-color photograph-like performance and video speeds. However, in view of recent accomplishments showing near-video-speed switching and potential for full color, after electrophoretic displays obtain a slice of the reading market, application of these developments will take us a significant step towards full-color animated paper-like displays. The developments that have led to the presence of electronic paper in the market today will be described, and developments that are about to happen will be discussed.

Ionic thermoelectric materials, for example, polyelectrolytes such as polystyrene sulfonate sodium (PSSNa), constitute a new class of materials which are attracting interest because of their large Seebeck coefficient and the possibility that they could be used in ionic thermoelectric SCs (ITESCs) and field effect transistors. However, pure polyelectrolyte membranes are not robust or flexible. In this paper, the preparation of ionic thermoelectric paper using a simple, scalable and cost-effective method is described. After a composite was fabricated with nanofibrillated cellulose (NFC), the resulting NFC–PSSNa paper is flexible and mechanically robust, which is desirable if it is to be used in roll-to-roll processes. The robust NFC– PSSNa thermoelectric paper combines high ionic conductivity (9 mS cm À1), high ionic Seebeck coefficient (8.4 mV K À1) and low thermal conductivity (0.75 W m À1 K À1) at 100% relative humidity, resulting in overall figure-of-merit of 0.025 at room temperature which is slightly better than that for the PSSNa alone. Fabricating a composite with cellulose enables flexibility and robustness and this is an advance which will enable future scaling up the manufacturing of ITESCs, but also enables its use for new applications for conformable thermoelectric devices and flexible electronics.

Q Is for Quicken Final Presentation
15 August 2014
Sha Xin Wei
Intel Research Fellowship
Copenhagen Institute of Interaction Design

The goal is to create a poetically composed essay in the physical form of manipulable sheets of material that feel like paper but can emit speech-quality sound modulated by touch and pressure.  We  will make a limited edition of a 14-page essay “Q Is for Quicken” realized as a printed object in which the content of some pages is heard, not read.  This work’s magic comes from sheets of physical paper that speak or sing when handled or touched.  A design goal is to break the gimmicky limit of greeting card + sound on a chip, and discover more poetic gestural modulation of paper animated by sound / haptic transducers and touch sensing.

As part of the Fellowship PhD researcher Chris Wood (Queen Mary  University London) and Sha Xin Wei taught a workshop on Paper and Sound in April 2014.