Wearable Continuous Temperature Monitor

This armband continuously monitors body temperature while you sleep. You can monitor temperature hands-free from another device, even if you're in a different room.

You can monitor temperature for up to 8 hours on a full charge (tested on a 3.3V 400mAh lipoly battery, data sent to Adafruit IO once every minute). Data is sent to your Adafruit IO account for long-term storage and visualization. Use Adafruit IO Triggers to be notified by email when the temperature increases past a set threshold.

Bluetooth Low Energy (BLE) Temperature Armband

Monitor your (or someone else's) temperature, hands-free, from anywhere with the Adafruit Feather nRF52840.

Temperature readings are sent from the Feather nRF52840's Bluetooth-Low-Energy (BLE) radio to the Adafruit BLE Connect App.

Interactive Temperature Dashboard

Adafruit IO is the easiest way to stream, log, and interact with your data. This project uses Adafruit IO to log and display temperature data on an interactive dashboard. You can check the current thermometer reading and monitor the temperature over time.

Fever Email Alerts

If a temperature threshold is reached, your armband sends an email to your phone.

Hands-Free and Rechargeable

We've designed this wearable armband to hold a rechargeable 3.7V 400mAh lipo battery. The Feather NRF52840 has an on-board lipo charger - plug it into micro-USB to charge between uses.

About your Health Data and Adafruit IO

We won't share your account information with anyone without your permission and everything you store on Adafruit IO is private by default, whether you're a paying customer or not.

We believe Internet of Things devices should come with a well established expectation of what they will and will not do with consumer’s data.

About this Project

  • This project is not a medical device.
  • This project is not waterproof or water-resistant
  • This project is not designed for use with children.


The parts below were used in this project. You don't have to use the exact same parts but the enclosure was designed to specially fit these parts - so if you want to use different components, you can but just know it may not fit in the provided enclosure. You can of course tweak the CAD files.

Angled shot of a Adafruit Feather nRF52840 Express.
The Adafruit Feather nRF52840 Express is the new Feather family member with Bluetooth Low Energy and native USB support featuring the nRF52840!  It's...
In Stock
Angled shot of blue, rectangular, microcontroller.
The Adafruit Feather Bluefruit Sense takes our popular Feather nRF52840 Express and adds a smorgasbord of sensors...
In Stock
Angled shot of a small, blue, rectangular temperature sensor breakout board.
This I2C digital temperature sensor is one of the more accurate/precise we've ever seen, with a typical accuracy of ±0.25°C over the sensor's -40°C to +125°C...
In Stock
Breadboard-friendly SPDT Slide Switch
These nice switches are perfect for use with breadboard and perfboard projects. They have 0.1" spacing and snap in nicely into a solderless breadboard. They're easy to switch...
In Stock
Slim Lithium Ion Polymer Battery 3.7v 400mAh with JST 2-PH connector and short cable
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
Out of Stock
10 wire Silicone Cover Stranded-Core Ribbon Cable
For those who are fans of our silicone-covered wires, but are always looking to up their wiring game. We now have Silicone Cover Ribbon cables! These may look...
In Stock


Having the right tools makes this build easier and more fun. Most of these are available in the shop but use whatever tools you have on hand.

1 x Soldering Iron
Hakko FX-888D
1 x Flush Cutters
Flush diagonal cutters - CHP170
1 x Wire Strippers
Hakko Professional Quality 20-30 AWG Wire Strippers
1 x Panavise Jr
Panavise Jr. - PV-201
1 x Helping Hands
Helping Third Hand Magnifier W/Magnifying Glass
1 x Screwdriver
65 Piece Ratchet Screwdriver and Tool Bit Set


Wires, screws, magnets, filament - The supplies listed below are both helpful and necessary for completing this project.  

1 x 3D Printer Filament
Filament for 3D Printers in Various Colors and Types
1 x Heat Shrink
Multi-Colored Heat Shrink Pack - 3/32" + 1/8" + 3/16" Diameters
1 x Solder, Rosin-Core
Mini Solder spool - 60/40 lead rosin-core
1 x Micro USB Cable
Pink and Purple Braided USB A to Micro B Cable - 2 meter long

This guide was first published on Apr 07, 2020. It was last updated on Jun 23, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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