MagPen - A Novel Way of Digitizing Notes Using Magnets

29 Dec 2014

A mobile device has a multitude of sensors ranging from GPS to a barometer. One sensor that is used daily is the capacitive sensor. Capacitive sensors detect anything that is conductive and they are used for touch input in mobile phones. We rely tremendously on touch input to interact with our devices ranging from playing games to checking notifications. We also have the ability to use our finger or styluses to write notes directly on a mobile device. However, touch/stylus input on mobile devices has its own set of problems. We are unable to easily draw detailed diagrams or write notes using the touch screen.

Is there another way to provide a different method of digitizing notes with a mobile device that expands the capabilities of touch? Another sensor that can be used for alternative methods of interaction is a magnetometer. The magnetometer senses changes in the magnetic field in all three axes (x,y,z) [10]. If the magnetic field can be detected, then it is possible to alter the magnetic field by using an external magnet. When the external magnet is moved around, it will alter the magnetic field thus producing different (x,y,z) values.

MagPen is a system that allows the user to digitize notes while they are written on a sheet of paper. The pen itself contains magnets or it can be an electromagnet. As the pen moves around in the area next to the phone, the changes in the magnetic field are detected and they are mapped out onto an x-y plane. To simulate an actual pen, the pen will only emit a magnetic field when the tip is pressed down. That allows the phone to only recognize actual pen inputs and not the pen movements.

To enable a richer set of interactions, the magnetic field strength can be used to control various pen attributes, such as stroke size or color. This is accomplished by moving the magnet based pen closer and further away to control the size of color.

There has been existing work in the industry that attempts to solve this problem. A few examples are Livescribe, Equil JOT, or the Wacom Tablets. This devices however require additional devices and/or special pen and paper to be able to digitize these notes. MagPen attempts to remove the need of additional devices by just requiring your mobile device and a custom pen.

To read more about this, take a look at the project writeup here.