INEXPENSIVE BRAILLER: Writing Braille Using IMPAD - Courant ...

Figure 3.1.1: IMPAD. The picture of the IMPAD, also called UnMousePad, because it looks
like a mouse pad but does not require a mouse.
3.2 Technology
IMPAD consists of five layers: the first and fifth layers consist of parallel wires [5]. The wires on
layer 1 are designed in parallel and they are perpendicular to the direction of the parallel wires on
layer 5. The second and fourth layers consist of resistive material which allows a current between
adjacent wires of layer 1 and layer 5. The third (middle) layer consists of a material whose
electrical resistance decreases when compressed allowing for the sensing of outside forces [5].
When external pressure is applied to the sensor, a path is created that allows current to
flow from layer one to layer two, and through the point of contact in layer three [5]. Then it
flows along layer four and finally passes an electrode in layer five. The proximity of the contact
point from an intersection and the pressure exerted at that point determines resistance of the path
created when the pressure is applied [5]. Then the path‟s resistance specifies the resulting voltage
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