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Droplet – Evolve your FreeStyle Libre to a CGM

The Droplet is a new small bridge released in July 2019 to evolve a FreeStyle Libre sensor (FGM – Flash Glucose-Monitoring) to a Continuous Glucose Monitoring (CGM) system. The Droplet reads the current glucose value every 5 minutes from the Libre via NFC and sends it by Bluetooth Low Energy (BLE) to your phone. You simply attach it to your sensor and once you replace your Libre you only have to recharge the Droplet to restart the cycle. I bought mine at the official Droplet store for $145.63 (~ 135€).

Features

  • rechargable – every 14 days
  • 100% waterproof
  • working with Libre, Libre 2, Libre Pro, Libre H.
  • firmware updatable by user via nRF Connect application
  • working with Spike, xDrip

Firmware upgrade

Instructions: https://droplet.rocks/en/blog/manual/firmware-update-instruction

Firmware downloads: https://github.com/MarekM60/Droplet-FW

LED Codes

  • Charging: blue blinks every few seconds
  • Fully Charged: blue light is continuous on
  • Droplet restart: 2 red blinks
  • Firmware update finished: continuous red light (You now need to restart the droplet)

Attaching the Droplet

I am using a special tap called Fixomull to secure it.

XDrip+ setup

Instructions: https://droplet.rocks/en/blog/manual/xdrip-setup-for-droplet

Calibration will take some time and some values will possibly be missed, but I had to learn that some waiting sometimes causes miracles.

Restart

If you ever need to restart the droplet you can restart the droplet by holding the magnet of the charging cables end close to the droplets top.

(2 blinks confirm that firmware restarted with success)

Troubleshouting

If you have troubles getting data there are several points to look at:

Never got data from sensor?

  • Check “Transmitter PL” support to be enabled in XDrip+ (check here)
  • NFC antenna broken? Check with idiab-test app

Connection lost / sensor stopped working:

  • Wait some minutes … sometimes I just had to wait at least up to 20 Minutes – even if its hard 😉
  • Check sensor position / reposition sensor
  • Restart App / XDrip+ collector (3 Bars -> system status -> restart collector)
  • Restart bluetooth / phone

Test app (dev.idiab.iDroplet.apk)

If you want to check if the sensor is broken, use Mareks test app. It only works for Android as far as I know, but searching for it on the Apple Appstore wouldn’t hurt 😉 . For Android download it from Github.com and install it (you have to allow unknown sources). Before you can find your Droplet in the test app you have to unbind it in XDrip+ (3 bars -> system status -> forget device) or any other already connected app. Now you only have to press on “Scan” and wait at least 30 minutes, because the Droplet is only sending data every 5 minutes. If you got some test data, send a screenshot to the Droplet facebook group.

Each line is one transmission (every 5 minutes):

time >> bluetooth message << length (20)

Content of Bluetooth message:

  • first – raw BG * 1000 and sensor type (229810 = 229.8 mg/dl and last 2 digits: 10 = Libre 1, 20 = Libre 2, 40 = Libre Pro/H)
  • second – battery voltage in mV
  • third – battery %
  • fourth – time since sensor activation for L1 and LPro, time since Droplet reboot – L2. Time is in minutes / 10

Result:

If you get a message every 5 minutes with a length of 20 characters with 4 fields in the message your Droplet should be working fine. If your Droplet is not correctly placed on the sensor it wont send anything and if you receive the same message over and over again your Libre sensor is expired / broken.

Review

My sensor arrived after about one week. I was quite impressed how nice it worked after I figured the initial setup with xDrip out. Sadly I broke my first sensor at the first date of using it, because I couldn’t resist going kiting. I contacted the Facebook group and with the help of Marek we figured out that my sensor wasn’t sealed correctly. Marek instantly offered me a replacement, that he already shipped the next day. At this point I have to say this guy is amazing. I cannot think of any company which would have responded that fast and would be that helpful as well.

After more than two weeks of successfully using my replacement sensor I can now really recommend this tiny helper to anybody being interested to get the Libre 1 data continuously. For the Libre 2 I guess the patched version of the official FreeStyle App for Android should be preferred, because you wont need a second device on you arm.

The Droplet bridge isn’t the only one on the market. For example there is also the well known MiaoMiao reader. They announced to release a second version in the end of August 2019 which will be worth a try. But I went for the Droplet, because I couldn’t wait and the shipment from Poland should be much faster.

Disclaimer

This article is a small documentation and experience collection. It does not have to be complete nor error free. You any information on your own risk. I have bought the Droplet myself and have no profit-oriented contact with the manufacturer.

Feel free to comment or ask questions (Gerne auch auf Deutsch) and check out the Droplet Facebook group.

Author: Anton Bracke

Software engineering student from Germany. Loves programming in PHP, JS and sometimes C.

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