uECG - small open source wireless ECG sensor

So, this happened - uECG is again available on Tindie! 

It may be a couple months behind our original schedule (we aimed for May/June, now it's mid-August), but it's here now! On the way, we made a new device case 3D model (and 3D printed a lot of them!) and a new packaging design, ordered all kinds of supplies and accessories, shot a new video and took new product pictures, rewrote most of our description here and on Tindie from scratch, and had to figure out how exactly do we sell at all - with the new shipping rules regarding VAT in Europe.

Now that we did all of this, stock is back, and sales are open again! There's some updates on Tindie regarding shipping, but other than that it's pretty much the same as before - at least where the product and its options are concerned. In regard to the product page content, however... there's major changes. All of the text is rewritten, there's now a very detailed list of features, and the new pictures look nicer! We really like how the page looks now (we didn't before...).

uECG v.4.5. itself has a few differences with the previous versions - most of which we mentioned in the previous logs - like adding external sticker antenna and an IPEX1 connector and removing optocoupler (more on hardware changes in this log). Software-wise, we added OTA firmware update via Android app and a support for standard BLE connection, so uECG can now be seen as a standard BLE heart monitor in other apps (including popular fitness apps). For that, we rewrote A LOT - the bootloader had almost nothing in common with previous one. Some more good news: the new bootloader will be compatible with all previous uECG versions! We've finished writing it for new devices and will be adding compatibility over the next couple weeks. Meaning theoretically (we're 99% sure) any uECG we made can have the possibility of wireless firmware update and can be seen as a BLE device - possibly including even the 2.2 version. It will require updating the bootloader through wires with a programmer like STLink v2, however.

Anyway, time to see the new uECG 4.5 trailer! 

We've decided to create this log to keep uECG-related events and news in a single place. It will be updated whenever something new happens, so keep an eye out!

March 22, 2023

uECG is back and we have reopened sales! It’s a small batch, so get them while you can! We have made some changes to the board that will hopefully make it (especially the IMU) more reliable and efficient. 

As always, we will try to ship your orders within 3 days, but they can take longer after sales reopen.

Changelog for uECG v.4.52:

- Replaced AD8606 op amp with a pair of TLV271s;
- LDOs (3.3V for digital, 3V for analog side) were mixed in the previous version; strangely this didn’t affect functioning, but now this is fixed;
- Replaced BMI160 with LSM6DS3TR-C;
- Changed C6 capacitor from 2.2uF to 10uF for better low frequency performance;
- Replaced circuit protection (red LED) with diodes for more reliability;
- Changed charge resistor to 8.2K Ohm to fit the battery charging better;
- Replaced MCP71831 charger IC with TP4054; 
- Added thermistor for measuring temperature;
- Changed RGB LED to different part number;
- Added Ultimate Robotics logo on the back of the PCB.

November 26, 2022

We have launched our second device, uMyo! It's a single-channel EMG sensor with both wet and dry electrodes. You can check it out here. Also, we wrote a small post about the blackouts in Ukraine (which you've probably read about in the news) here. Check it out, bet you've never seen anything like this.

June 10, 2022

We have reopened uECG sales today (and a large firmware update)

June 7, 2022

A tribute to our friend, veteran and fellow maker, Denys Antipov

March 17, 2022

War update #2 (volunteering and living from day to day)

Feb 28, 2022

War in Ukraine (that's where we are) update

Feb 14, 2022 We're back from vacation, although we still wait for a new batch of uECGs. It's due in 7-10 days - until then, we have a few devices in stock. Also, Happy Valentine's Day!

Jan 19, 2022 New batch of uECGs in early February - we'll reopen then, as we decided that despite still having a couple uECGs left, we better use the time to upgrade our packaging/shipping process and prepare for the spring. See you soon!

Jan 16, 2022 Extended the break for a few days to take inventory and order new production batch, stay tuned

Dec 28, 2021 We're taking a break until January, 16! Happy holidays to everybody!

Nov 16, 2021 We're back from the break! And we also have extra gel electrodes back in stock, as well as a fresh batch of USB bases from the factory. The bases are slightly more expensive now ($14 instead of $10, as the component prices have gone up). Other than that, everything's back to normal!

Oct 26, 2021 We are on vacation from today to November 14! Time to rest a bit, we've been shipping slower recently. Feel free to sign up for notifications about when we reopen.

October 13, 2021 update Extra packs of gel electrodes temporarily removed from order options, cause we run out of them and the new ones are arriving in a week or so. We'll still put 10 free gel electrodes with each order, we just can't put more of them.

August 24, 2021 update Bug with radio mode (about which we wrote on Sunday) is now fixed and all orders until now are shipped! Thank you for your patience!

August 17, 2021 - uECG returns - with new features! Well, it’s clearly taken longer than a month since we sold out all stock in April - in fact, it’s now late July, but we’re launching uECG sales again! uECG v4.5 has new PCB layout, some new components (and some removed), better antenna, more battery life (24 hours, finally!) and new firmware improvements! We have implemented standard BLE connection (so fitness apps can now recognize uECG as a generic heart rate sensor), better signal packaging for BLE version (previously R peak amplitude in BLE mode wasn't as precise due to the averaging method), and more reliable R peak detector. And we also made another big step - wrote a brand new bootloader, so you can now upload new firmware directly from the Android app!

April 2, 2021 - New uECG stock in a month Well, we have officially almost run out of uECGs. There's only a couple devices left. We're preparing a new batch to send into production in April, and it'll (probably) be ready at the start of May - but who knows, maybe there'll be delays at the factory. We can hope though!

Latest app version here:

uECG monitor app on Google Play.

Feb 3, 2021 - Arduino library

Official Arduino library is online.

Dec 9, 2020 - EMG mode is working!

We play Cyberpunk 2077 theme cover with EMG gesture control using uECGs in this Hackaday log.

Sep 9, 2020 - New app functions

Hackaday log about the app update - Poincare plots, HRV, accelerometer data.

Sep 1, 2020 - Wireless firmware upload is ready!

All units ordered after September 1st have wireless firmware upload capability. Older units require uploading new bootloader via ST-Link once, after that they will support wireless update as well.

A USB base station is required for this process - BLE is not supported yet.

To turn uECG maintenance from slightly painful to pleasurable activity, we made it possible to update firmware directly from the app! This process currently takes about 2 minutes, but all you need is a phone and uECG.

How did such a technological breakthrough become possible, you ask?  It's the new bootloader. When we added support for the full BLE protocol, we had the opportunity to reliably (albeit slowly) send data to the device - and this, in principle, is all that's needed to update the firmware. Surprisingly, even with BLE support, bootloader size is still less than 16 kb - so we will use it in the future too.

Firmware upload process will be described in more detail later in the Instructions section - for now you can watch it in our new video!

We have been thinking for a long time how to make uECG more accessible, in the sense of making it user-friendly - data processing, a nice multi-functional UI, a cloud for storing user data... But dreams don't always hurry to come true...

Anyway, in the new uECG version we wanted to do something for everyday use. So we did just that.

Now uECG can connect as a standard Bluetooth heart rate monitor and display heart rate and RR intervals in a standard format. That is, if you use running app in which you can connect devices / fitness trackers, then you can now add uECG there and monitor heart rate changes - and if the app supports this function, then also the RR intervals!

We cannot name specific apps because this is considered using someone else's brand for advertising purposes - but we've tested a few popular ones and they all work. In theory, any app of this type should understand our data format - we made a short video of how this works in some of them.

You can also add uECG support into your own apps much more easily now (we'll write some documentation on this, once we have some time).

With that, we have at least made uECG more approachable!

Perhaps not everybody knows, but in April 2021 we sold the last uECG device from the first batch we made after the Indiegogo one. Naturally, we were optimistic and planned to launch production in April at once, but - you guessed it - not everything went as planned...

Partially it was because in this production run we supplied our own components to the factory and this new method required more time to buy and ship the components (and to research how to supply them correctly). But also because we wanted not only to re-produce another batch, but to make the device more functional. To do this, it was necessary to add / rewrite the firmware and make a component revision.

What has changed?

1. Added a standard Bluetooth connection (BLE). Although the data transfer rate has not changed much, there are fewer lost packets.

2. Added an external antenna for better signal - the antenna on the board was too close to the skin and was not as efficient. Now your heartbeat can be displayed even more reliably! This is a sticker antenna that is connected to the board through an IPEX connector and stuck to the case from the inside, so the device will remain the same size.

3. Added / removed a number of components: namely, removed the optocoupler, changed the power circuit for the nRF52832 to an internal dc-dc, partially switched the voltage to 3.0 V, and changed the method of powering on the device (now the on-off switch only turns on the battery power, but the device itself is turned on by a tact button).

5. Finally pogo pin contacts have small holes in them and won't slide - we have moved them from behind the USB connector to a position which had free space over it on the top side, so we were able to add the holes.

4. These various PCB changes prompted a 3D printed case upgrade (as some elements changed position), and now it fits even better.

6. At last, we were able to defeat power consumption and now our 200mA, 501245 battery will last a whole day!

7. Improved signal data packing for the BLE version (previously, the peak amplitude R in BLE mode could be inaccurate due to the averaging method)

8. Last but not least - the R-peak detector has become even more reliable!

But the most crucial improvements, in my humble opinion, we will share in the next posts.

We're really excited about this new uECG version!

Two days to Cyberpunk 2077 release, we made it. 
Yesterday we finished a working prototype of wireless, wearable EMG interface that can control something. It uses uECGs as channels, and it is an update to previous logs we wrote on that topic. Since then, we added neural networks and it takes around a minute to train it.
The control is not ideal, and it feels unusual to play music like this - but it's there, and it's working. 

We think we're onto something here.

With all of the internet plastered with Black Friday ads, we've decided to add our share to the enthropy and put uECG on sale - but that's not all we're adding.

We've wanted to have more color options for 3D printed cases for the longest time, so we bought and tested a lot of filaments. We particularly liked a pastel PLA set from Monofilament (a local Kyiv manufacturer), but they lacked a pink one, and couldn't find any other available in Ukraine. Eventually we ordered a test 200 gram spool of pastel pink PLA from taobao and it turned out really well.

So now uECG cases come in five colors - black, pink, yellow, turquoise and white (a nice milky tone). It'll be on sale on Tindie for $69 (which puts the price of a full set with the BLE receiver base at $79) for another two days.

What uECG can currently do:

- stream realtime ECG signal

- calculate BPM, HRV, Poincare plot

- get and save data in Android and node.js (cross-platform) apps - yes, that means that you can use it on Windows too!

- stream for 12-18 hours nonstop

- update firmware wirelessly

- as of recent, it also has EMG mode

- and, of course, it's fully open source and open hardware - and will always be. 

So basically, it packs a lot. 

If you don't need a uECG though, you can still go check out the new pictures and colors!

...and if you didn't want to check out the new colors, you just did anyway :)

Before moving on to the technical details of today's update, here’s the background story. More than a year ago, more or less at the same time we were finishing uECG, we began to develop uEMG. In parallel with this, having launched a crowdfunding company, we made a promo video where we showed that uECG can be used to measure electromyography.

A couple of months ago, a person wrote to us and said that he saw that video and needed a device to measure EMG. We really wanted to have time to finish uEMG this year, but life circumstances (and pandemic) forced us to deal with other issues... So we suggested him to use uECG to measure EMG. For this, we have significantly updated the software part and now we are also working on improving the UI.

That actually required rewriting the whole radio stack - previous protocol had a major bug, and overall wasn’t well suited for multiple devices. We ended up making a kind of a library with all the important functions we use in most projects - radio, timer, UART - all our further code will use it (and so its functionality would be growing over time). The main difference vs Nordic’s softdevice approach is full control over what is happening and when exactly (so for instance radio processing won’t interrupt time-critical interactions with peripherals), and clear understanding of what exactly is happening under the hood.

Changes are so significant that we decided to add a bit more functions into uECG firmware and call it Mark II (even though hardware is the same, so all previous devices can be upgraded). The new version of this firmware will be released soon. 

Now for the EMG part: each device performs on-board 8-points FFT calculation and uses relation of spectral bins 1-3 vs bin 0 to determine EMG activity level (since a lot of EMG signal is located at 100+ Hz area, and not a lot of random noise appears there). This calculated level is indicated with LED colors - at first we tried to encode it in brightness level alone, but it wasn’t clear enough, so at first it increases brightness of blue channel, and with further rise goes into pink and then cyan colors, thus making it easier for visual interpretation. And it’s also sent out to the base station, together with calculated spectrum. 

New radio protocol now implements discovery, and the base station polls data from all discovered devices within a short cycle (2 milliseconds per device). Sometimes packets are lost, so practical latency is often 2-3 times higher than the best case scenario, but still it’s quite close to realtime.

We have made a video where you can see our jack-of-all-trades, master of none Dmitry playing the piano, with simultaneous recording of data from devices (ordinary charts represent calculated EMG levels, and spectral charts show the FFT data calculated on-board).

Happy viewing!

We were so deep in Maker Faire preparations that accidentally posted two logs about the event authored by two different team members. Anyway, the last one has more useful links, so we decided not to delete it and just edited a bit.

Main Empire State Maker Faire 2020 page. The event is live from 16 to 17th October, with Friday reserved for more student and school-oriented events and the rest for the Saturday. 

So our stream's today (Oct 17) 10:30 EST. Come chat! 

Link to the stream here: https://makerfaire.com/maker/entry/72841/

Our project on Make Projects: https://makeprojects.com/project/uecg---smallest-open-source-ecg-wearable

All of the events: https://makerfaire.com/empire-maker-faire-2020/empire-state-schedule-page/

We'll be streaming live this Saturday on Empire State Maker Faire! We'll be showing our home workshops, devices new looks and abilities, and generally talking about open source stuff and plans on Saturday, Oct 17, from 10:30 to 11:15 EST (that's 17:30 Kyiv/Eastern European time). 

https://makerfaire.com/empire-maker-faire-2020/empire-state-schedule-page/ 

There are lots more cool events there, so be sure to check out the Maker Faire schedule. We're personally hyped for the 12,000 masks, Genspace and Public Libraries Print PPE ones - and we'll also be sure to check our as many makerspace tour streams as we can!