mePAP - Low cost, Multipurpose, Equitable, Positive Airway Pressure Device
The mePAP consists of a simple 3D printed housing, with a 12V brushless DC motor blower unit, a motor driver, and pressure sensor encased inside. Some current devices have an added humidification unit to warm the air to increase comfort levels. The devices are fully functional without this addition, and hence it was removed to keep costs low, while keeping comfort high. The mePAP is controlled through an ergonomic app, making it easier to set the pressures especially during the night. The app also allows for data collection, with open access to breathing data throughout the night, which is currently withheld on many PAP devices. Current PAP devices range from NZD $800-$2500, with the mePAP only NZD$250. This reduction in cost makes it more equitable for lower-socio economic users, who are more susceptible to sleep apnea. No current PAP devices to date connect to, or utilize external sensor systems, which ensures this project is making a step forward from current state-of-the-art. The additional mini sensor at the mouthpiece provides another level of accuracy with a feedback response implemented to ensure the pressure the subject receives is as close to that set, along with giving more accurate measurements to base BiPAP and APAP control from. This mini sensor unit has been designed to fit at the end of the hose and connect to the mask with ease, being small and light weight to minimise disruptions to the user. Files are split into two main sections: Code; and Hardware. Code files include the mobile phone app for control, ESP32 code for CPAP, BiPAP, APAP and mini sensor control, and Matlab code for plotting of results. Hardware comprises of 3D printed components and printed circuit boards (PCB's). Both the main mePAP housing and the additional mini sensor 3D printed components are available as SolidWorks parts and STL files. SolidWorks files can be adapted to suit user needs, or STL files for direct 3D printing as is. Hardware PCB's contains the control PCB and pressure sensor PCB. Both can be adapted as required.
Steps to reproduce
To construct the device, the instructions are as specified: Place an order for the PCBs and appropriate parts required for population. The motor and driver should also be purchased at this time. Print all 3D printed parts in the mePAP folder with appropriate layer height (eg. 0.015mm) and support material. Support material was removed with pliers. Once arrived, populate the PCBs. For the ESP32 board first solder on the capacitors, resistors, and wire connectors. Solder female socket headers into the through holes for the ESP32, before mounting it. The pressure sensor PCB requires resistors, the pressure sensor, and a capacitor to be soldered. The 3D printed venturi has pressure sensor port guide holes drilled out using a 1.6mm drill bit. Using a Stanley knife the pressure sensor port copper tube was cut to a 5mm length and inserted into the venturi hole before being glued in place. The bottom of the tube must be flush with the interior surface of the printed venturi tube for accurate pressure readings. Use minimal glue to prevent any blockages. Flexible silicone tubing connects from the pressure sensor port to the port tubes on the venturi. This tube length can be adapted to fit the layout of the mePAP. Acoustic foam was cut to the size of the mePAP base with a craft knife. A layer of hard foam was inserted on the base with a layer of acoustic foam placed on top. A hole for the motor and venturi were cut out of the second layer for room. The motor, driver, and pressure sensor were then placed inside with the PCB and motor cords threaded out the small hole in the back of the base. A single layer of foam was then placed on top of all components for further noise reduction. Six M3 bolts where then screwed used to attach the front and top panel to the base to enclose the box.
University of Canterbury