Intraoral Respiration Monitor & Overdose Detector

Full waveform respiration monitor worn inside the mouth + streaming Bluetooth web app. Uses barometer, thermopile & hacked activity monitor.

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A wireless full waveform respiration monitor worn entirely inside user's mouths (intra-oral) that streams data to a Web Bluetooth enabled web application.

The device measures the air pressure, humidity and skin temperature inside the user's airway. In short, BME280 air pressure sensor + MLX90615 thermopile thermometer + hacked miniature nRF51822 based activity tracker mounted on an ultra-thin custom dental retainer.

My primary goal is to detect opiate overdose. Depressed respiration is the best way to detect overdose and the only approved indicator for the administration of Narcan (Naloxone). Full waveform respiration data is surprisingly difficult to obtain. Spirometers, chest-straps and pulse oximetry (including photoplethysmogram) are relatively inaccurate - particularly when respiration becomes depressed. There are many potential applications and the device could be built using other form factors (bite stick, mouth guard, integration into tracheal intubation

This device was built using MATTER Labs hacked smartwatch based prototyping platform. Check it out on Hackaday!




1) Hack an activity monitor with components small enough to 'comfortably' fit in the top of my mouth.


2) Add sensors that can accurately track the full respiration waveform, in other words we want to track the entire inhalation/exhalation cycle including strength and speed of both inhalation and exhalation.

3) Build a custom retainer to which we can attach all our electronic components. This will anchor them in place and also act as a barrier between the components and the user's skin. 

4) Build  a smartphone app or Web Bluetooth web application that can receive, analyze and visualize streaming data from our intraoral respiration monitor.  


This project has a couple twists that make it particularly fun. First, electronics don't like to get wet. Mouths are wet. Waterproofing the device could be as easy as dipping it in epoxy - but - this would render both of our sensors useless. Our air pressure sensor has an inlet that must access the air in the oral airway - otherwise we are just measuring the air pressure inside a tiny epoxy (or whatever) sealed chamber. Our thermopile sensor gives us the temperature of whatever solid surface it is pointed at. If we seal of cover the device, the thermopile sensor will be pointed at whatever is covering or sealing the device - so we'll just get the temperature of the interior of our sealed device. In addition to waterproofing there is the size and comfort issue. We are trying to build something that, eventually, users can wear in their mouth without even noticing its there. If test users can wear the device for half an hour without pain and verbally communicate in a garbled but intelligible matter the device is a success. If I can get that far with tiny budget and simple tools I can safely assume that additional resources would result in a future version that meets my 'real life' requirements.


MCU Datasheet

Adobe Portable Document Format - 7.02 MB - 03/28/2018 at 00:35


KX022-1020 Specifications Rev4.0 cn.pdf

Accelerometer Datasheet

Adobe Portable Document Format - 1.98 MB - 03/28/2018 at 00:35



Air Pressure Sensor Datasheet

Adobe Portable Document Format - 1.85 MB - 03/28/2018 at 00:35



MCU Manual

Adobe Portable Document Format - 1.43 MB - 03/28/2018 at 00:35



Thermopile Contactless Thermometer Datasheet

Adobe Portable Document Format - 827.19 kB - 03/28/2018 at 00:35


View all 6 files

  • 1 × BME280 Bosch Combined humidity and pressure sensor w/ I2C interface
  • 1 × MLX90615 Melexis contactless thermopile thermometer w/ I2C interface
  • 1 × Bondo or Casting Resin
  • 1 × Dental Vacuum Thermoforming Hard Plastic Sheet
  • 1 × Needle and Thread (standard sewing kit materials) For attaching electronic components to custom retainer

View all 13 components

  • 1
    Create a Custom Dental Impression - Alginate Negative Impression

    The respiration monitor electronics are built into a clear ultra-thin custom retainer. This retainer keeps the sensors and other electronics correctly positioned and also acts as a protective barrier between the electronics and the sensitive skin inside the user's mouth. The first step in creating this retainer is a negative impression of the upper teeth using dental alginate. 

    Materials and workspace

    The finished negative impression

  • 2
    Create a Custom Dental Impression - Bondo Positive Impression

    The fragile alginate negative impression is used as a mold to create a tough heat resistant positive impression. The positive impression will be used to form the specialized dental thermoplastic sheets into ultra-thin ultra-clear retainers. I use Bondo because I had some in my apartment and it is very easy to use. Heat resistant casting resins or silicone rubbers could probably also be used though they will have to be pretty tough.

    Use a thin rod ( I used a 1/8" diameter barbecue skewer ) to poke out any air pockets deep down in the individual teeth cavities. Major air pockets anywhere in the impression will cause problems later when it is heated to 230 degrees C. I did two batches to Bondo, the first to fill the teeth and the second to create a structural base. Bondo adheres to itself very well, especially if it hasn't cured yet.

    The finished positive impression. I used a Dremel cutting tool to trim down the impression as much as possible. This is important because the dental thermoform sheets must be able to curve around the impression as if it were a real part of your body. Gaps and holes are inevitable with this crude process. I use epoxy to fill in any obvious air pockets.

View all instructions

Enjoy this project?



Luke Z wrote 10/18/2021 at 18:50 point

This project is super cool! Could you share more info about the process to do the waterproof for the barometer and get the air pressure reading? Thank you very much.

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eproperty.tere wrote 07/05/2021 at 13:11 point

Sound good. Is this good idea to use in live experiment? I want embed it in my website of dental centre .

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Ever wrote 04/23/2018 at 17:18 point

Great project

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Robert Mateja wrote 04/14/2018 at 10:35 point

I'm sure Jamie Lee Curtis from 1999 Virus movie will approve ;)

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