Paper‐Based, Capacitive Touch Pads

Abstract

Table of Contents:Mazzeo et al. describe methods of patterning metallized paper to create touch pads of arrayed buttons that are sensitive to contact with both bare and gloved fingers. The paper-based keypad shown detects the change in capacitance associated with the touch of a finger to one of its buttons. Mounted to an alarmed cardboard box, the keypad requires the appropriate sequence of touches to disarm the system. Image for Table of Contents:Submitted to 2 This paper describes low-cost, thin, and pliable touch pads constructed from a commercially available, metallized paper commonly used as packaging material for beverages and book covers. The individual keys in the touch pads detect changes in capacitance or contact with fingers by using the effective capacitance of the human body and the electrical impedance across the tip of a finger. To create the individual keys, a laser cutter ablates lines through the film of evaporated aluminum on the metallized paper to pattern distinct, conductive regions. This work includes the experimental characterization of two types of capacitive buttons and illustrates their use with applications in a keypad with 10 individually addressable keys, a keypad that conforms to a cube, and a keypad on an alarmed cardboard box. With their easily arrayed keys, environmentally benign material, and low cost, the touch pads have the potential to contribute to future developments in disposable, flexible electronics, active, "smart" packaging, user interfaces for biomedical instrumentation, biomedical devices for the developing world, applications for monitoring animal and plant health, food and water quality, and disposable games (e.g., providers of content for consumer products).There is no simple method of integrating buttons with structures on single-use or throwaway devices. Current commercial buttons are not thin enough, inexpensive enough, or easy enough to array seamlessly with paper-based products for disposable applications. The touch pads in this work are thin (~60 µm in some cases), simple to array, fabricated by etching patterns into metallized paper, low-cost (< $0.25 m -2 for the thin grade of metallized paper we use in this work), and lightweight (100s of g m -2 ). The individual keys measure changes in capacitance when touched by a user, and the buttons require no physical displacement of conductive elements. Even though the individual keys on the touch pads detect changes in capacitance, the paper-based keypads are still functional when touched by fingers in nitrile gloves. Submitted to 3Developments in paper-based electronics include ring oscillators with organic electronics [1] , transistors [2][3][4] , methods for patterning conductive traces [5][6][7] , speakers [8] , super capacitors [9] , batteries [10] , MEMS [11] , and solar cells [12] . Each of these developments focuses on a single technological advance that would enable new types of consumer products. Many types of new consumer products will require some form of user interface or input. In order to gather ke...

Electrically Activated Paper Actuators

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