Improving the reliability of smartwatches for everyone.
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At Plethys, we develop solutions for smartwatches to ensure that users are getting the most out of their wearable device to support a healthier lifestyle. Plethys takes its name from the technology used in heart rate sensors, photoplethysmography, which is the focal point of our work.
There are nearly 300,000,000 smartwatch users around the world today, and that figure is expected to rapidly expand at a compounded annual growth rate of ~9% between now and 2030. While smartwatches are engineered for the general population, they simply do not work for everyone. We estimate that around 5% of all smartwatch users (11.5M people worldwide) are having problems to consistently acquire their biometric data.
The products offered by Plethys are attachment devices for smartwatches with an embedded optical lens that refracts the lights from the heart rate sensor, creating a light tunnel, which allows for biometric readings to be captured in the toughest of conditions. Founded in San Diego, California towards the end of 2023, Plethys is excited to launch the first product fleet in Q4 2024.
To enable underserved populations to lead healthier lives by restoring and stabilizing heart rate sensor signals on wearable devices.
To influence future smartwatch innovation and to create a customer voice for smartwatch users that cannot benefit from the promised biometric and security features that come with their smartwatch.
Plethys Founder and CEO, Andrew Gladue, became an early adopter for smartwatches in 2014 and quickly discovered that his tattoos prevented him from obtaining useful measurements of his sleep, workouts, and overall health. After seeing another tattooed triathlete wear their smartwatch on their ankle, he had a call to action to address this problem in a meaningful way for smartwatch consumers.
* Andrew has over 15 years of relevant industry experience, possessing an MBA from San Diego State University, and holds two of the most prestigious supply chain certifications (APICS CSCP and CPIM).
Plethys helps smartwatch users who want to have consistent biometric data by preventing sensor signal loss issues through an affordable and sustainable solution, unlike any other option that would require wasteful damage to the device or another expensive device to be worn and maintained.
The BIG Problem With Smartwatches
The red and green lights that flash on the back of a smartwatch work in tandem to capture biometrics, but neither wavelength is good for total skin penetration and daily motion. Users with tattoos, darker skin tone, obesity, and/or dense body hair most frequently experience gaps in their heart rate data that create issues with their biometric readings and overall wrist detection. The smartwatch's software algorithim relies on these readings for nearly everything that makes the watch "smart". These are known issues captured in the accuracy disclaimers by most smartwatch manufacturers.
Missing Sleep Data
Gaps in Activities
Poor Detection of Stress/Illness
Watch Battery Drains Faster
Passcode/Theft Problems
Can't Pay From Watch
Joe Rogan on Instagram
Social media post from celebrity Joe Rogan in July 2023 where he was excited to own a Garmin watch. However, he then needed to purchase an expensive heart rate chest strap to track his activities because his tattoos block the smartwatch heart rate sensor.
Media Coverage
The problem has started to capture media attention. We expect coverage of the problem to increase in the coming years.
Accuracy Disclaimers
Manufacturers acknowledge the problem, but do not offer a solution for impacted users. These accuracy disclaimers can be found on the manufacturer's website and/or within the packaging of a purchased smartwatch.
Law Suits
Manufacturers are beginning to face consumer lawsuits over the problem. These types of disputes are often settled out of court. We expect to see an increase of legal challenges over time as user adoption increases.
Social Media
Gen Z and Millennials with tattoos have formed the loudest customer voice on social media. TikTok, Reddit, and Instagram are common places to express grievances and offer workarounds. Some users are damaging their device with nail polish remover, hot glue guns, and rashy stickers to temporarily address the problem. Some even resorting to tattoo removal.
How to solve heart rate sensor problems
Plethys found inspiration from grassroots online communities seeking to solve the problem at home. Some smartwatch users have found that adding a clear or semi-translucent material to the back of the watch can re-activate the sensor and restore lost functionalities. However, these solutions have risk for skin irritation, aren't sustainable, and may damage the device. Our efforts have been focused on understanding why some of these user-generated modifications have worked, and how this can be best offered in a durable, safe, and cost-effective manner. Our solutions are offered as accessory products to smartwatches with no additional hardware or software needed, and will work with any smartwatch.
The Science
The root of the problem is based on light travel from the back of a user's watch not reaching their blood pulse. Light studies have demonstrated that prisms can both refract and tunnel light to create optical paths that reduce distance and increase displaced strength into desirable areas of interest. This concept is important for smartwatch technology as the bottom of the watch, where lights are emitted, is susceptible to ambient lighting and conditions in addition to obstructions from a person's physical characteristics. Bridging this gap is critical.
Scalability
Our solutions are scalable for both data integration and affordability. Some users have resorted to purchasing an expensive heart rate chest strap or smart ring to pair with their smartwatch. These are not practical for everyone due to cost, comfort, fashion preferences, and data synchronization. Additional devices can cost more than the smartwatch itself. Our solution has a low cost to produce which is passed onto the consumer - similar to purchasing a bottle of laundry detergent. By using our products, the consumer can consolidate their electronic devices without requiring any new apps nor risks for data integration.
Optical Lens
An optical lens placed between the watch and the user's skin serves as a prism and acts as a light guide or light tunnel to deliver a more effective heart rate signal. The optical lens must be durable and breathable to sustain sweat, steam, various forms of liquids, low to high temperatures, and resistant to chemicals found in pools and hot tubs. The optical lens should not trigger known skin sensitivity problems. The lens needs to have translucency to refract the lights from the heart rate sensor and allow the smartwatch to obtain biometric data. The optical lens is treated as an add-on accessory, comparable to cell phone cases, and does not permanently change or damage the watch or void any user warranties.
Attachments
An optical lens is only useful for a smartwatch if the lens is reliably on the watch through everyday movements and activities. The lens should also be both removable and reusable to confidently allow for cleaning and recharging. Watch chargers have different requirements, with Apple having the most stringent charging field requirements. Accumulated dirt, grime, and sediment on a watch is standard for expected smartwatch cleaning. Our attachment solutions are focused on the customer experience, where a user can trust that the optical lens is on the device when desired but can also be easily removed and re-used. Current workarounds shared online today do not account for these considerations.
Evidence
Below are examples of smartwatch biometric data with and without our product. This demonstrates both the problem and the solution, which are easier to identify in sleep data, workouts, and daily heart rate levels.
[click on the image to expand the view]
Garmin (without Plethys)
The user went to bed without our product at 10:30pm and had a restful and uninterrupted 8 hours of sleep. However, the watch had missing (estimated) readings throughout the day, and it began tracking sleep ~2 hours later than what the user confidently believed. The watch then stated that the user was awake for 2-3 hours in the middle of the night, which the user confidently rejects as happening. These errors commonly occur on Garmin when the software attempts to overcorrect itself for a lost heart rate signal. The user felt refreshed and energetic in the morning after achieving their sleep target of ~8 hours, but the app stated that they slept much less and that they should feel fatigued.
Garmin (with Plethys)
This user experiment was completed with our Plethys product. Here we can see strong continuous readings throughout the night and day. We do not have any estimated readings, and have accurately tracked all of the sleep cycles throughout the night. The user qualitatively reported waking up at around 5am, tossing and turning before their alarm clock went off. This is accurately captured, and the guidance provided from the app about their sleep quality is valid and useful. The user reported being anxious about a stressful day at work.
Garmin (without Plethys)
This user experiment was completed without our Plethys product. This time we are focused on the results from Garmin's "body battery" reading, which shows how much energy you have available. Typically we like to see a reading over 70-75 for rest & recovery. Because of the poor sleep performance calculated in the previous slide, the data is showing that the user should take it easy. We also observe the overall heart rate performance which has 3 significant gaps generating "estimated" readings in Garmin's software. This means that the watch stopped tracking the user during critical times, invalidating all of the information.
Garmin (with Plethys)
This user experiment was completed with our Plethys product. Here we can see that the user had full continuous sensor readings throughout the night and day. This allows the user to optimize their true biometric rest and recovery. Since there are no gaps in the heart rate data, the software does not try to estimate any of its readings ensuring trust and validity. The user found that they went to bed with greater stress the night before which negatively impacted their sleep. The user benefited from this information by improving their wind down routine that following evening.
Apple (without Plethys)
This user experiment was completed using an Apple Watch without our Plethys product. The user was completely unable to track their sleep due to Apple's software algorithim requiring continuous wrist detection. When the heart rate sensor signal is lost, even for a few seconds, the watch believes that it is not being worn and locks itself. Apple also requires that a preset sleep schedule is saved and synchronized, or that sleeping mode is manually turned on and off from the watch. The user must have sleeping mode working correctly for 4 hours to capture any sleep data. In this instance, wrist detection caused the failure.
Apple (with Plethys)
This user experiment was completed using an Apple Watch with our Plethys product. Here we can see that wrist detection worked throughout the night, and that the user was able to obtain all of the sleep stages along with a heart rate report from their sleep. It is still critical that the user presets a sleeping schedule or manually activates sleeping mode from their watch. This is a general requirement for Apple Watches. Plethys was able to solve the problem of wrist detection that was demonstrated in the previous slide.
Apple (without Plethys)
This user experiment was completed using an Apple Watch without our Plethys product. In this test, we had the user complete a 45-minute running activity without any perspiration prior to starting the run. The watch was successful in starting the activity, but it stopped tracking after ~8 minutes. The user reported that the watch appeared to be recording the entire time and had no awareness that the activity forcefully ended on the watch. We can also see that the readings started off stronger in the first 30 seconds, and then became faint and intermittent until the watch stopped tracking. This could be attributed to sweat, rigorous motion, and an already faint heart rate signal.
Apple (with Plethys)
This user experiment was completed using an Apple Watch with our Plethys product. We asked the user from the previous slide to re-attempt a 45-minute running activity with our product. Here we can see that the run was fully captured and completed. We did notice an inexplainable pause in heart rate during the beginning of the run, but the power and pace readings remained intact. The runner stated that he stopped halfway through at a traffic light and checked to see if the watch was still recording without engaging with the watch. Overall, we observed strong continuous readings with our product. A massive improvement compared to being without our product.
FAQ
How do I know if I have a problem with my smartwatch?
Great question! It's difficult to know directly from the watch -- unless you have a heart rate indicator on your watch face, are getting frequent passcode requests, or cannot complete mobile payments from the watch.
The best way to check is to look at your mobile app or web dashboard. Start by looking at your daily heart rate data for any noticeable gaps in the report. If you record your workouts and activities, you may notice drops in your performance when you were actually pushing yourself. Sleep data is another giveaway. Make note of when you go to bed and when you wake up, and compare the results the following morning. Any gaps, estimates, or completely missing datasets are indicators that you're having a smartwatch heart rate sensor problem and cannot trust your biometric data.
What's different about your product from the other workarounds I've seen?
For starters, we are the first company to address this problem. Our products are proprietary and patent-pending. We are taking this solution beyond any other known workaround today for the best customer experience possible.
We are up to speed on all of the "hacks". If they work for you, great. But for us they just resulted in new problems and failed to address our expected experience with smartwatches.
Yes, we've tried the epoxy stickers. They will end up loose in your sheets or fall off during the day. They also gunk up your sensor with residue and have to be constantly replaced.
We strongly do not advise putting nail polish remover on your watch. It's a strong chemical that isn't good for both your watch or your skin. This will likely cause permanent inaccuracies and lead to other hardware malfunctions.
The same can be said for sanded-down hot glue gun drops over your sensors. It's not a great idea to burn the back of your watch and permanently deface it. You may permanently prevent it from charging, let alone ever get an accurate reading again.
Let's throw films and electrode gel into the trash bin as well. The films have very poor refractive peformance. The gels have an unsettling texture and will create a mess.
Have you heard of a hack not listed here? Let us know! We're more than happy to investigate and show why our products are a better option.
Why are you called Plethys?
We know the name is new to you. And we're here to tackle a new problem on old science!
We are named after the scientific technique to obtain physiological information through noninvase optical methods, called photoplethysmography or PPG for short. A silly person also observed that our product is in the middle of the device and the user. Technically we should be called Plethysmo in that context, but that's not as fun to communicate. The first PPG measurements were taken in 1937, nearly 100 years ago! This is the same technology used for a routine doctor visit where a fingertip pulsometer captures your blood pressure. Brilliant minds found that if we incorporated the technology into a smartwatch, and utilized it with various software algorithims, that we could obtain all kinds of meaningful insights to guide and encourage our daily health. It's what makes the smartwatch "smart"! Unfortunately, there isn't a good color spectrum that returns the signal for everyone. Long story short, we're obsessed with the potential of photoplethysmography and we know it isn't going away.
Will your product work with any smartwatch?
It sure does! We are constantly in the lab working to improve both our optical lens and attachment methods. Any standard smartwatch with a circular, square, or rounded-square watch face will be able to use our first product fleet. We are working on a solution for slim rectangular watch faces such as the FitBit Inspire 3, that should become available later in 2025.
How much will your product cost?
Our initial product offering is intended to be very affordable and universal. Our goal is to be in the range of a 12-pack of beer or a bottle of laundry detergent. Once our first production run is complete, we will communicate a price point to our followers before launch.
Can I try your product for free?
Our beta tester program is open for a limited time to try our product for free. We take any and all feedback seriously and would love to know what you think and how our product works for you. Click the "Free Product" link in our menu above.
What does the product look like? How can I find out more?
Please follow our social media channels for teasers and early releases. We want your voice to be heard too! Please use our social media channels as a sounding board to show the smartwatch manufacturers that we're tackling a problem worth solving!
Will you offer watch cases?
We're working on it! We understood from early customer trials that our product adds a thickness to the watch that prevents standard smartwatch cases from being used. We have already designed and started testing embedded watch case enclosures. We expect these to be offered as a slim sporty model, as well as a luxurious "Swiss style" offering for that premium look when you need to dress up.
Contact Us
Have a question or want to know more about us? We'd love to hear from you. Give us a call, send us an email, or use the form below and we will get back to you as soon as we can.
+1 (619) 777-6262
1286 University Ave #1046, San Diego, CA 92103, USA
Customer Service:
support@plethys.com
Press:
press@plethys.com
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