AbsolutSweat Real-Time Sweat and Hydration Biosensor Review

As a triathlon coach and endurance athlete, I’m always on the lookout for tools and devices that can provide useful data to optimize performance.

The AbsolutSweat Real-Time Sweat Tester caught my attention as a potential disruptor in hydration and electrolyte management. After unboxing and testing the device (you can check out my unboxing video and sensor attachment demo on the ChiliTri YouTube channel), I’ve got some insights to share.

Unlike other sweat testers this device is re-usable and shows you your real-time sweat data during your training sessions so can help you to get your hydration spot on so you can perform your best.

AbsolutSweat Unboxing

Before we dive into how to use the AbsolutSweat sensor let’s look at what you get when you order the device.

What’s inside the box?

The sweat sensor is well packaged in thoughtfully designed recyclable packaging. The contents include:

• AbsolutSweat Sensor / Tracker
• Charging Case
• USB-C Charging Cable
• Box of twelve sweat patches
• Patch unit replacement tool
• Instruction Booklet

It’s well worth taking the time to watch the quick start video on YouTube to help you with the correct set up.

AbsolutSweat Unboxing Video on Chilitri YouTube Channel

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Product Specifications

Size: 100mm x 52.2mm x 21.7mm

Capacity: 300mAh


Weight: 72g

Energy: 1.11Wh


Voltage: 3.7V

Price: $249.99 / £197 / €237 from the Liipoo website (the link will give you 12% off)

AbsolutSweat contents with Sweat Sensor, patches, charge case and documentation

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AbsolutSweat App Setup

The device itself is compact, lightweight, and relatively easy to use. It comes with a sensor and adhesive patches that collect sweat for real-time analysis.

The first thing to do when you unpack the contents is to activate the sensor by putting into the charging case. When orientated the right way the sensor LED will flash, and the case LED will blink once and shows the sensor is charging.

The next step is to install the App on your phone. You can get the App from the Apple App store or from Google Play site.

Enter your basic data in the App then pair the App with your AbsolutSweat sensor. You can do this by scanning the QR code, entering the 8-digits of the MAC code or search for the sensor which needs to be close to your phone.

You then need to attach the sensor to the patch to the sensor. The case that the sensor comes in is an impressive design and double as charging station and a neat way to connect the sensor to the adhesive patch. You can see how to do this in my video below:

Attaching the AbsolutSweat sensor to the sweat patch on the ChiliTri YouTube channel

AbsolutSweat Sensor Patch Attachment to your Body

Make sure your phone Bluetooth is switched on and you can “see” the sensor. Press the “start a workout" button in the App and select the workout type appropriate to your training session. I was intedning to do an indoor rowing session so had to set up a custom sport and entre the parameters. You also need to enter the type of hydration type you will use - in my case it was pure water.

The AbosolutSweat App and Initial Set Up

Ensure you wipe your skin to take off any lotion etc so you can get good adhesion. They recommend placing the sensor on your upper chest but after three attempts I found that I didn’t sweat much in that area during my workouts, making it difficult to collect sufficient sweat data.

After reaching out to the AbsolutSweat customer support team, they advised trying the base of my spine instead.

This turned out to be a much better placement for sweat collection, especially during my cycling, rowing and running sessions. If you’re struggling with insufficient sweat collection, I’d highly recommend this alternative placement.

This is the preferred placement position of the AbsolutSweat on your upper chest

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The App: Ease of Use & Data Insights

The AbsolutSweat app is user-friendly and intuitive, making it easy to set up and sync with the sensor. Once connected, the app provides real-time feedback on sweat rate, electrolyte loss, and hydration levels.

The interface presents data in an easy-to-read format, including graphical trends over time, which can help athletes adjust their hydration strategies based on workout intensity and environmental conditions.

One particularly useful feature is the personalized hydration recommendations, which suggest optimal fluid and electrolyte intake based on the collected data. This allows athletes to make informed, real-time hydration adjustments to prevent dehydration and performance dips.

The app is available for both iOS and Android and integrates well with other fitness tracking tools.

After setting up your sport type, prompts, target expenditure setting and connect the sensor you can start your workout.

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During your training session you can use the App to see your real-time sweat loss and re-hydration records. You can enter the type of drink you are using so it can analysis how this affects your sweat.

If you lose connection don’t worry as the sensor will collect the data and upload to the App once re-connected.

After the session the App will give you recommendations for you next training session.

After your session you need to peel off the sensor and remove the patch from it. Clean the sensor well and replace into the charge case for storage and re-charging.

Using AbsolutSweat: Performance & Accuracy

Once properly positioned on the base of my spin, the device performed well, providing real-time feedback on sweat rate and electrolyte loss. The first session I did with the AbsolutSweat sensor in this new position was an indoor rowing session which would really test the location as I hinge from my hip when rowing and this will move the sensor.

The data synced with the app, making it easy to track trends and adjust hydration strategies accordingly. Research suggests that sweat rate and electrolyte composition vary significantly among athletes, so having a personalized approach can be a huge advantage (Baker, 2017).

One of the key benefits of this device is its real-time feedback, allowing for mid-session hydration adjustments. I was able to keep an eye on the App from my phone to understand my water, Sodium (Na) and Potassium (K) loss and when I needed to rehydrate. It reminded me to rehydrate at the 40 minute mark.

My feedback on the AbsolutSweat App during my rowing session showing water, sodium (Na) and Potassium (K) Loss

Studies show that dehydration as little as 2% of body weight can significantly impair endurance performance (Sawka et al., 2007). This tool helps prevent that by alerting athletes to their hydration needs before performance suffers.

In the initial 30 minutes of my indoor rowing session, I did not see any real time sweat updates on the App which got me a little worried. But after about 35 minutes the App sprang to life and started to show me real time updates and advice.

The AbsolutSweat app will alert you if your glucose or electrolyte levels are low, helping you avoid injuries. You can get accurate metabolite readings without a lab and receive hydration reminders on your phone, Bluetooth headphones, or watch.

AbsolutSweat App showing my post workout stats and advise

You can get a personalized plan based on your age, height, weight, and health. No more "just drink when thirsty". Supplement the right amount of water, electrolytes, and nutrients to your body at the right timing. Recharge faster and perform better!

The data you will get includes water loss, weight loss, Sodium (Na+) & Potassium (K+) loss, glucose level, fatigue tolerance, dehydration tolerance, sweating rate, hydrated state, post-workout replenishment, fluid intake record, rehydration time recommendation and energy supply recommendations.

AbolutSweat showing my post workout advice including my sodium and potassium curves, fatigue index and  training expendure.

For my rowing session the app advised me to replensih my sodium but there was no need to replenish my potassium. It suggested there was not need for carbs but suggested some protein (20-40g) within one hour after my workout. I lost 635ml of sweat per hour. Both my sodium and potassium trend lines were considered normal.

At the end of the session, you can send your results to your coach but at this time it is limited to WeChat which is popular in Asia. It would be good to get this extended to WhatsApp which is popular in Europe and the US plus email. You can download the results file or take screenshots to share with others.

AbsolutSweat Accuracy

You can be assured of the quality of your data. Here’s how AbsolutSweat ensure lab-level accuracy in sweat test and analysis: 

• One-of-a-kind biosensor technology: They utilize biosensors that capture electrical signals from sensitive materials reacting with metabolites in your sweat. This technology ensures optimal sensitivity, minimizes interference, and provides consistent results.

• Extensive testing: Over the past 5 years, their team of more than 60 research and development engineers has conducted ongoing testing with athletes, sports schools, and research institutes worldwide. Their data closely matches results from biochemical laboratories, and some test outcomes for professional athletes can be viewed here.

• Quality control: Their production process for sweat patches is fully automated, using coating machines to apply sensitive materials uniformly and consistently, maintaining high-quality standards.

• Expert-led research team: Their R&D team is led by a distinguished expert featured on Stanford University's Global Top 2% Elite Scientists 2020 List. This leader also holds fellowships with prestigious institutions such as the American Institute for Medical and Biological Engineering, the Royal Society (UK), and the European Academy of Natural Sciences.

The AbolutSweat patch showing the biosensor and electrical details

AbsoluteSweat Uses

Having your personal sweat data will help you ensure you are hydrated correctly before, during and after a training session. Here are some of the ways it can help you.

1. Pre-Race Hydration & Energy Planning

One of the biggest challenges an endurance athlete faces is delaying fatigue while maintaining peak output. AbsolutSweat allows you to assess your sweat rate and electrolyte loss, helping you build a precise pre-race hydration and fuelling plan. Instead of relying on guesswork, you can go into race day with confidence, knowing your body is primed for optimal performance.

2. Post-Race Recovery & Rehydration

Recovery is just as critical as performance, and AbsolutSweat helps streamline the process. By providing data-driven hydration and supplement recommendations, it ensures you’re replenishing efficiently—helping to reduce muscle soreness, improve recovery speed, and maintain peak condition for your next session. Especially for athletes juggling tight training schedules, this kind of precision can be a game-changer.

The AbolutSweat sensor in the charge case with sweat patches

3. Post-Workout Replenishment Without Overload

Refuelling after training is essential, but overcompensating can be just as detrimental as under-hydrating. AbsolutSweat helps you strike the perfect balance by offering personalized intake recommendations, ensuring you get exactly what your body needs without unnecessary excess. This is particularly useful for athletes focused on performance gains, weight management, or endurance longevity.

4. A Valuable Tool for Coaches & Trainers

For personal trainers and coaches, AbsolutSweat can be a valuable asset in designing individualized hydration and nutrition strategies for clients. Every athlete has unique hydration needs, and having access to real-time sweat analysis allows for tailored energy plans that can improve both training efficiency and performance outcomes.

The AbsolutSweat sensor and charging case in the ChiliTri Athlete Testing and Therapy Room

Absolute Sweat Pros & Cons

Pros:

✅ Reusable sweat rate sensor you can use at home – no need to go to a laboratory.

✅ Real-time sweat and electrolyte analysis you can view as you work out on the App.

✅ Lightweight and comfortable once properly placed.

✅ Helpful and responsive customer support.

✅ App integration for tracking trends over time.

Cons:

❌ Placement matters! You may need to experiment with sensor placement to find the right spot for accurate data collection. My best position was the base of my spine

❌ The adhesive patch might not stick as well in extremely humid or wet conditions (e.g., during open-water swims).

❌ Sending the results is limited to WeChat right now – it would be useful to send via email or WhatsApp.

❌ The sweat sensor does need a sweat patch every time you use it so you will need to buy more over time.

AbsolutSweat works with SUUNTO and Garmin Smart Watches

Conclusion: Final Verdict of the AbsolutSweat Real-Time Sweat Tester

The AbsolutSweat Real-Time Sweat Tester is a valuable tool for endurance athletes looking to fine-tune their hydration strategies – before, during and after a race or training session.

While the initial placement recommendation didn’t work for me, the company’s customer support helped me find a more effective location, and from then on, the device worked as expected.

If you’re serious about hydration and electrolyte balance, this device is worth considering.

Have you tried the AbsolutSweat device? Let me know your experiences by emailing me at karen.parnell@chilitri.com.

Karen Parnell is a Level 3 British Triathlon and IRONMAN Certified Coach, 8020 Endurance Certified Coach, WOWSA Level 3 open water swimming coach and NASM Personal Trainer and Sports Technology Writer. 

Karen is currently studying for an MSc in Sports Performance Coaching at the University of Stirling.

Need a training plan? I have plans on TrainingPeaks and FinalSurge:

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I also coach a very small number of athletes one to one for all triathlon and multi-sport distances, open water swimming events and running races, email me for details and availability. Karen.parnell@chilitri.com

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FAQ: AbsolutSweat Real-Time Sweat Biosensor

1. How does the AbsolutSweat Real-Time Sweat Tester work?
The device uses a sensor and adhesive patch to collect sweat and analyse hydration and electrolyte levels in real-time. The data is synced to an app for easy tracking.

2. Where is the best place to attach the sensor?
Initially, the company recommends placing it on the chest, but I found better results positioning it at the base of the spine during workouts.

3. Can the device be used for all types of exercise?
Yes, it can be used for a variety of activities, including cycling, running, indoor rowing and gym workouts. However, placement might need to be adjusted based on sweat production.

4. Does the adhesive patch stay on securely during workouts?
For most athletes, the adhesive works well. However, if you have particularly dry or oily skin, you might need to ensure proper skin preparation for better adhesion. Make sure you clean your skin well before placing the sensor on your body.

5. How accurate is the device?
Studies suggest that sweat rate and electrolyte data can vary per individual, but real-time tracking allows for a more personalized hydration strategy.

6. Is the device compatible with all smartphones?
The Absolute Sweat app is available for both iOS and Android. Check the app store for compatibility with your device.

7. What should I do if I’m not getting enough sweat data?
Try adjusting the placement to an area with higher sweat production, such as the base of the spine. If issues persist, contact customer support for further guidance.

8. Can I use the AbsolutSweat sensor when swimming?

No, AbsolutSweat is not suitable for use during swimming. The sweat patch needs to react with enough sweat and then sends data signals back to the AbsolutSweat app. Water in the swimming pool or sea can dilute your sweat, leading to inaccurate test results.

9. Can I use my AbsolutSweat with a Smart Watch?

Yes, you can see your data on Garmin and SUUNTO watches which more integrations like the Apple Watch coming soon.

References

• Baker, L. B. (2017). Sweat Testing Methodologies in the Field: Challenges and Considerations. Journal of Applied Physiology, 122(3), 562-570. https://doi.org/10.1152/japplphysiol.00024.2017
• Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine Position Stand: Exercise and Fluid Replacement. Medicine & Science in Sports & Exercise, 39(2), 377-390. https://doi.org/10.1249/mss.0b013e31802fa199