Overdose Detection Necklace + App

ODAlert is a wearable opiate overdose detection device with supporting smartphone app

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This device is the first in a series of projects exploring wearable device solutions to drug overdose and drug addiction. The device contains an accelerometer, a PPG optical heart rate sensor and a thermopile contactless thermometer to detect skin temperature. The device also contains an extremely loud buzzer and is connected to a smartphone app which is capable of alerting an emergency response team. The emergency response feature is currently a mockup and does not actually function. The general idea is that the device uses sensor data to detect a possible drug overdose event. The device then activates its buzzer. If the user does not deactivate the buzzer after an allotted period of time it is assumed that an overdose is taking place and the device alerts emergency responders through the connected smartphone app.

Here are some Amazon and Ebay links for the more obscure/specific materials. No doubt these will quickly become obsolete.


ID107 nRF51822 based Generic Activity Tracker:



Printable STL file for 3D printed electronics enclosure locket adapter.

Standard Tesselated Geometry - 80.16 kB - 04/03/2018 at 22:05



Blender 3D modeling file for 3D printed electronics enclosure locket adapter.

blend - 20.60 MB - 04/03/2018 at 22:05


  • 1 × 1"x1.5" Oval Locket There are tons of variations on Ebay and Amazon. Just search for "oval locket".
  • 1 × ID107 nRF51822 Generic Activity Tracker Any small nRF51 or nRF52 based activity tracker will work but in this tutorial we'll use the ID107
  • 1 × MLX90615 Thermopile Contactless Thermometer
  • 1 × Internally driven 3.5v mini buzzer This has a resonator built in. Don't get a buzzer that requires an external signal. Diameter: 12mm, Current:
  • 1 × SMD style micro switch

  • 1
    Hacking a nRF51822 ARM Cortex-M0 Generic Activity Tracker

    Starting with a generic activity tracker saves a huge amount of time and cost. This is what they look like on the inside. Usually 90%+ of mass market electronic device manufacturing costs are upfront factory equipment and facilities. Raw material and labor cost are usually extremely low. Because of this a $20 activity tracker will often have the exact same components and build quality as a $300 device. 

  • 2
    Modify Hacked Activity Tracker Enclosure

    Carving up activity tracker enclosure so it will fit into 3D printed locket interface. Holes for wires etc.

  • 3
    3D Print Hacked Enclosure to Locket Interface

    I modeled an adapter to connect the back half of the activity tracker enclosure to the modified locket. You can 3D print this adapter yourself using files attached to this project.

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RobertHunt wrote 12/03/2019 at 10:31 point

Wow that's a cool invention

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