Design Overview (Final Design)

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.

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.

The complete assembly of the device

How the Device Works

The device takes the form of a headset. Essentially, the user will attach the device to their face using the CPAP straps, ensuring that the chin guard fits snugly onto their chin and their tongue can reach all five copper contact points. If not, the user can adjust the CPAP straps accordingly.

Once the device is fitted, the device needs to be connected to a computer that is Bluetooth compatible and runs CircuitPython. The device’s code will search for the computer’s Bluetooth signal, and once available and connected, the device will be ready to use.

With five copper contact points, the device contains nine total capacitive buttons (5 single touch buttons and 4 chord buttons (two adjacent double touch buttons)). The buttons themselves each have two different responses, one from a short hold and the other from a long hold. To the right is a figure of the layout of each button.

TrainingSoftware.mp4

Above: Photo of Stacy training with new device

Diagram representing device's capacitive touch buttons

Video on the left: Stacy training with software that explains the functions.
The Image below: Functions shown according to each contact points

Key Components

Include 4 major parts:

Chin Guard, Food Safe Coating, Head Strap, Capacitive Touch Contact Points and Wires

Frontal View of the Chin Guard

Top View of the Chin Guard

CAD of the Chin Guard

Chin Guard

Overview

The “Chin Guard” is the central component of our design that every other component will be attached to. It needs to maintain its integrity for a long lifetime. Therefore, the functional requirements for this component are more extensive as well as necessary to fulfill.

Functional Requirements

Needs to be comfortable enough to wear for 8+ hours a day → With the application of silicone putty and the chin guard itself fitting to Stacy's chin, according to Stacy's feedback he feels good!
Must be durable, stiff, and easily washable → The 3D printed model is more durable than the Halloween mask used before and has already been washed several times during testing then still works well!
Must enclose several “Capacitive Touch Contact Points” → The contact points increase from one to five!
Should have ventilation to prevent sweat build-up → There are always holes on "The Ingenium" model

Final Design Components

Slots for housing the copper wire (capacitive contact points)
Curved Radius and Inner Pads for stable fit on chin
Anchor points for CPAP strap attachment
Ventilation holes at the bottom
Saliva channels to prevent buildup and saliva capacitive bridges

Senior_Design_May_ExpVid_V5.mp4

CAD Animation of the Chin Guard Assembly

Food Safe Coating - MAX CLR epoxy resin

An epoxy resin food-safe coating is applied to “The Ingenium” and copper contact points in a one-time application. First, we have to make sure the device is hygienic. Contamination due to saliva will lead to the proliferation of bacteria, which could get Stacy sick. Applying hydrophobic coating on the surface of the capacitive sensor will reduce the buildup of saliva and thus lead to better hygiene. The coating will also allow better ease of use and care. Furthermore, the protective layer will keep the whole device intact for a more extended time.

MAX CLR Epoxy Resin was chosen as its functions complied with all our functional requirements, listed below.

Functions

Is entirely food-safe and hygienic
Durable (is safe and sturdy for 8+ hours daily)
Does not inhibit our capacitive touch hardware (Copper Contact Points) and software
Easily adheres and protect Stacy from metal surfaces - Copper & Stainless Steel

Hydrophobic (Saliva can create various issues)

Head Strap

Overview

The “Head Strap” will function as the mechanism that maintains the “Chin Guard” connected to Stacy’s chin; therefore, it is essential that the “head strap” is firm yet comfortable. The “head strap” should also fulfill the following requirements.

A Philips Respironics CPAP Head strap accompanies by a Velour forehead strap was chosen as its functions complied with all our functional requirements, listed below.

Functions

Secures the “Chin Guard” to Stacy’s chin for 8+ hours per day
Attaches firmly yet comfortably
Can be adjustable to Stacy’s specifications which may alter slightly day-by-day
Remains in position even when Stacy is laying down and shaking his head

Capacitive Touch Contact Points and Wires

Overview

The “capacitive touch contact points” and “wires” together serve as the connection between the user’s tongue touch control and Adafruit CPB board. The pre-coded Adafruit CPB board, which is connected to the computer by either a micro-USB cable or Bluetooth connection, accepts touch signals from the user’s tongue which enables the user to control their computer. This complete system of “wires” connecting “capacitive touch contact points” from the user to the computer realizes the objective of a tongue-touch mouse and keyboard.

Functions

100% safe for the user to touch with tongue (with the application of food-safe coating)
Capacitive signal noise does not affect the proper functionality of the device
Any use of wire connection is be organized and secured, thus causing no safety concern for the user and people around
The contact points design are relatively easy for the user to manipulate and avoid inaccurate inputs

Label of pins that each copper wires are attached to

Full view of the device

Pins of Adafruit CPB Board

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