Tongue Touch
Mouse & Keyboard

Project Background

Many people in the US and worldwide suffer from some form of quadriplegia, which is defined as paralysis from the neck down, or all four limbs, as a result of an injury or deformity to the spinal cord region. Caused by vehicular crashes, falls, or through diseases such as childhood cerebral palsy, there are over 12,000 new cases brought up each year in the US alone [1].


StacyPlayingGames.mp4

Stacy Bibb is one of the many who suffers from cerebral palsy spastic quadriplegia. Despite this ailment, Stacy’s parents, Portia and Gary Bibb, wanted Stacy to retain some semblance of individualism and a greater quality of life. To make this possible, they began working with Jason Eldred, an Interaction Designer, to give Stacy the capability to control a computer using the part of the body he has the most control over, his tongue.

The Sponsor: Jason Eldred

  • An Interaction Designer the Bibb family is working with

  • Experienced at programming


Design Iterations:

  • Old Design: Retainer device with 9 contact points that went inside Stacy’s mouth

  • Recent Design: Single contact point tongue activated capacitive touch device

    • Can click, type and browse a computer by making contact with the copper wire (sensor) for different durations (tap, short hold, long hold)

  • While everything previously worked, there were issues with:

    • Headset comfort: makeshift plastic Halloween mask

    • Device movement and rotation: Two zip-tie attachment would rotate when pushed by tongue

    • Capacitive sensor reliability: Grabbing the wire causes capacitive interference and false positives


Project Objective: A new and improved design solving the listed issues!

  • Design a headset prioritizing comfort (sitting up and laying down)

  • Ensure reliability of capacitive sensors

  • Improve/add tongue touch inputs

    • Replace copper wire with more stable and safe material (ex. solid copper, stainless steel)

    • Overlay contact points with food-safe and hydrophobic coating

  • Design for headset reproducibility

  • Design chin cup specialized for Stacy’s proportions

    • Silicon putty for a comfortable and stable fit

  • Design for ease of Use/Care

    • Easy to put on/take off

    • Tongue sensor easily removable/washable (Hygeneie)

    • Electronics easily replaceable

Description of Final Design

The final design comprises of a wearable chin guard device, “The Ingenium”, that attaches to the chin with both a CPAP head strap and forehead straps. Five solid-core copper wires (our capacitive contact points) are each secured to the chin guard with plastic set screws, and are soldered to a CAT5 ethernet cable. The CAT5 ethernet cable is wired to an Adafruit CPB board which is powered by a computer via a USB cable.


The chin guard was 3D printed using an ELEGOO MSLA 3D Printer from a SOLIDWORKS CAD model. The chin guard was designed so that it conforms comfortably to the chin, is durable, is easily washable, and is compatible with every other part that must connect to it such as the CPAP strap and the copper contact points. The chin guard has a radius of 2.5” and it’s tightness on the chin is fully adjustable with the CPAP straps.

20210604_165702.mp4

Final Design Overview

The Adafruit CPB board is used to synthesize the capacitive signals it receives from the CAT5 ethernet cable which are first transmitted through the copper capacitive contact points. Depending on which contact point is touched, the Adafruit CPB board executes specific commands that allow a person to control a computer with their tongue.


Summary of Performance Results: Capacitive Touch & Stacy Testing

Capacitive Results

The two graphs on the left signify a test signal response from the both the pre-156B tongue touch design (pictured first) as well as the final 156B design (pictured second)

The first graph contains the capacitive signal response of a single touch as well as a test interference. The second graph contains the capacitive signal response of a single touch, double touch, and a similar test interference

(note, the test interference is simply gripping and holding the wires connecting the sensor to the Adafruit CPB)

Test Interference Results:

  • Pre-156B:

    • Test interference strength was 27.2% of its single touch response

    • Interference Signal infiltrated past the capacitive threshold

  • Final Design

    • Test interference was 2.5% of the single touch response

    • Test interference was 5.7% of its double touch response

    • Capacitive thresholds are well maintained and interference provides no threat of crossing.

Prototype Adjustments: Testing and Training with Stacy

Testing Conditions:

  • Team members went to Stacy's house and assemble the device for Stacy to test on

  • Stacy was asked for permission each time the device was put on him, and the device was cleaned each time before and after Stacy tried it on

Copper tabs poked Stacy's nose

→

Contact points now with copper wires

CPAP strap kept shifting backward

→

Sewing a Velcro forehead strap

Saliva build-up caused bridging

→

Increasing chin guard width and creating saliva channels

Videos

CAD Animation of "The Ingenium" Assembly

Senior_Design_May_ExpVid_CPAP_V5 (1).mp4
SeniorDesignTest.mp4

Device Demonstration (5x Speed)

Stacy Using the Device to Scroll Up & Down

UpDownStacy.MOV

Project Presentation

Final Design Presentation

SeniorDayFinalDesignPresentation.mp4

Final Design Slides

Final Design Presentation