Rapidkeypads helps an ALS sufferer - SGIA Journal July 2012

Using Rapid Prototyping to Give an ALS Sufferer His Voice Back

In this case, the ALS had caused paralysis throughout the person’s body except for a very limited use of the index finger on his right hand.

One of the nurses responsible for taking care of this person contacted RapidKeypads.com to see if they could help. The nurse wanted a device capable of being triggered by simply touching a button.

RapidKeypads.com proposed a simple solution.

They would make a custom device consisting of the Fast Touch system placed within an off the shelf enclosure. The Fast Touch system would be configured to consist of a touch sensitive button and driver electronics capable of producing high fidelity audio. This way when the patient touches the button and an audio sound would be produced. This sound would be interpreted as a call for help by the nurse. RapidKeypads.com views every capacitive touch keypad they create as a system.

They call it the Fast Touch System. Here is a video showing how fast it works!

A Fast Touch capacitive touch system consists of Fast Touch electronics, conductive circuit layer and graphic overlay.
Fast Touch electronics is the name given to all the electronics and firmware used by Rapid Keypads to produce a successful capacitive touch system.  At the heart of the Fast Touch electronics is the Fast Touch IC.
The various touch pads of the conductive circuit layer are connected to the Fast Touch IC.  The pads formed by the conductive circuit layer could be copper pours on a PCB or printed conductive elements on a film.  The overlay is non-conductive and placed on top of the circuit layer.  The overlay material could be glass, lexan, acrylic or any other plastic of various thicknesses.

When the human hand is brought in close proximity to the pads of the circuit layer, the capacitance associated with the pad changes.  This causes a change in the voltage measured on the pads.  This change in voltage is registered as a button press by the Fast Touch system.

As a function of this button press, the Fast Touch system can be configured to produce tactile feedback to feel every button actuation, produce audio feedback to hear a custom sound upon button actuation etc. The Fast Touch system can also be configured to communicate the button press and release data to the main controller using SPI, UART (RS232/RS485), I2C, USB HID communication protocol or a Simple High/low signal.

In the case of a medical device for the ALS patient, the Fast Touch System was configured to have one touch pad connected to a Fast Touch IC. When a button was touched, an audio feedback would be produced.

The touch pad used in the device was a conductive layer on a film. This conductive circuit layer on a film was digitally printed and connected to the driver electronics and configured to act in the desired way within 5 days. A picture of the device is shown above in the slider.

Not only can Rapid Keypads rapid prototype your capacitive touch interface, they also can manufacture capacitive touch keypads. They have been offering capacitive touch keypad design and manufacturing services to a diverse clientele in a range of industries.

Rapid Keypads understands that several aspects of the graphic overlay, such as inks and materials used, significantly impact the performance of the touch interface. By designing and manufacturing the graphic overlay and electronics together, they ensure a successful capacitive touch system. Their patented algorithms are equipped to deal with board to board parasitic capacitance variations which also include a variation in the input pin capacitance from one chip to the other from the same manufacturer. Mechanical stack-ups can vary about 30% especially when acrylic overlays are used to build capacitive touch system.

Not only does Rapid Keypads ensure that the mechanical stack up variations are under control, but their algorithms have built in tolerances to deal with these issues. For more information about their design and manufacturing capabilities please visit Rapid Keypads.

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