Today we have the honor of interviewing Stefan van der Fluit, CEO of FLOWBIO, a leading company that deletes dehydration for athletes.
FLOWBIO’s product, the S1, uses cutting-edge technology like microfluidics to isolate sweat in a clean environment off the skin surface. This allows them to measure sodium concentration in sweat far more accurately than existing methods. The FLOWBIO system also includes a companion app and machine learning algorithms that help athletes predict and manage their hydration needs, making it a comprehensive solution for endurance athletes and beyond.
Picture: FLOWBIO’s S1
Here is a picture illustrating where the S1 can be worn on the athlete’s body:
Picture: FLOWBIO
Here is below the pictures of FLOWBIO’s Compagnion App:
Picture: FLOWBIO’s Compagnion App
📝Show Notes: Through this interview, we touched on his background, his company and product, the benefits for sports organizations and teams to use his product. We also talked about his competitive advantage, business model, and his plans for the next 12 months.
You can read the full transcript of the podcast interview with Stefan located at the top of this blog post.
Here are some of the best quotes of our conversation with Stefan:
Q1. Tell me about your background.
"I grew up in the States, and my parents were both in technology—my dad worked for HP, and my mom was the entrepreneur of the family. Living in Palo Alto, the heartbeat of technology, I was exposed to amazing people, including the co-founders of Oracle. But because it was my normal, I didn’t put these people on a pedestal. I realized early on that it wasn’t rocket science to build game-changing or industry-changing companies; it was just everyday humans doing this. That gave me this almost blasé confidence—if you want to try something, just do it. If you fail, fine—do the next thing."
"I started my first company when I was 14. I couldn’t legally incorporate, so my dad had to sign the paperwork. I vividly remember him sitting me down and saying, ‘Don’t mess this up, because it’s my name on the line.’ It gave me a sense of responsibility but also a lot of support from my family. Since then, I’ve worked for companies like Facebook and founded multiple ventures. But for the last 10 years, endurance sports have been my life, and that passion is what led me to human performance technology."
Q2. Tell me about your company and product.
"FLOWBIO started because I wanted to solve a personal problem. As a triathlete, my Achilles heel was always hydration. No matter what I ate or how hard I trained, I’d hit the wall during the run leg. It was frustrating and limiting. So, my co-founder Giovanni and I explored different ways to address this. He came up with the system architecture for a sweat sensor, and I pushed it toward hydration—my pain point."
"Our product, the S1, uses cutting-edge technology like microfluidics to isolate sweat in a clean environment off the skin surface. This allows us to measure sodium concentration in sweat far more accurately than existing methods. The FLOWBIO system also includes a companion app and machine learning algorithms that help athletes predict and manage their hydration needs, making it a comprehensive solution for endurance athletes and beyond."
Q3. What are the benefits for your customers to use your product?
"The S1 gives athletes precise, actionable data about their hydration—how much water and salt they’re losing and what they need to replenish. It’s not just about hydration; it’s about advanced hydration. We help athletes understand the balance between water and sodium, which is critical to performance. Many people don’t realize that overhydration, or hyperhydration, is a common issue, where athletes dilute their electrolytes by drinking too much water."
"Another major benefit is that there are no ongoing costs. Unlike some of our competitors, our device is reusable and doesn’t require subscriptions or consumables. Once you have it, it’s yours to use as much as you want. Athletes appreciate this simplicity and transparency."
Q4. What do your customers like the most about your product?
"The feedback we get from customers is that they love how accurate and easy to use it is. If a product isn’t accurate, why would an athlete trust it? And if it’s hard to use, it’s just going to collect dust. We designed the S1 to be intuitive—it clips onto a chest strap and stays there. Once it’s on, you don’t have to think about it; it works automatically during every session, giving you sweat data without any hassle."
"Our customers also value the fact that there are no hidden costs. They don’t have to buy replacement parts or pay for a subscription. It’s a one-time investment for a product that delivers real value, day in and day out."
Q5. Tell me about competitive advantage and business model.
"Our competitive advantage comes down to two things: accuracy and usability. Athletes need to trust the data because their performance depends on it. Our device is highly accurate, thanks to years of research and validation studies. And it’s incredibly easy to use—no need for a PhD to understand the data or operate the product."
"Another key difference is our focus on science and engineering. We didn’t cut corners or rush to market; we spent over four years developing a product that’s supported by groundbreaking technology. This isn’t just about making something flashy; it’s about solving a real problem with integrity and depth."
Q6. Which sports do they currently focus on?
“"We have built the running, cycling, soccer/football, and tennis modalities. Those are the sports we can support today and are actively supporting. We’ve also been approached by motor sports, American football, and ice hockey, and we plan to build new modalities for these over time based on needs and priorities.”.
Q7. What are your plans for the next 12 months?
"2025 is going to be a pivotal year for FLOWBIO. We’ve just closed a funding round and doubled the size of our team in anticipation of scaling up. Next year, we’re ramping up production to thousands of units and aiming to make FlowBio a profitable business by the end of 2025. We’ll also be present at the biggest events in endurance sports, and we’re launching some exciting athlete partnerships that will bring more visibility to sweat monitoring as a critical part of performance."
"Beyond endurance sports, we’re expanding into new markets like tennis, football, and team sports. Each sport has unique hydration challenges, and we’re adapting our technology to address them. It’s a busy but exciting time for us as we continue to grow and push the boundaries of what’s possible in human performance."
Q8. What is the best way to reach out to you?
"The best way to reach me is WhatsApp. In the sports world, everyone’s always on the move, and WhatsApp is more immediate than email or LinkedIn. My WhatsApp number is +44 755 963 15873. You can also connect with me on LinkedIn or email me at stefan@flowbio.com. I’m always happy to chat with anyone interested in what we’re building at FlowBio."
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