How often – and how long – do people with obsessive-compulsive disorder stay in certain places? What can that tell us about their symptom burden? Can the length of a patient’s stride or fluctuating blood sugar levels predict recovery time after a stroke—and might improved data help shorten hospital stays?
Questions like these were nearly impossible to study until recently. But science and healthcare are now at a turning point—thanks to a digital solution that taps into something already present: the continuous data of daily life.
Millions of people wear smartwatches and fitness trackers every day—but their data rarely makes it to where it could have the biggest impact: research and healthcare. That’s starting to change. The goal is personalized medicine that is not only more efficient, but also fairer.
Each smartwatch or wearable medical device can generate tens of thousands—sometimes millions—of data points per person per day: heart rate, movement, sleep, respiration, skin temperature, and more. These data are now being collected in a joint study by Charité and Brandenburg Clinics—using a single platform. The aim: to explore how mobility and metabolic parameters affect rehabilitation outcomes after stroke.
“We combine wearable data with app-based questionnaires, which gives us a more complete picture of patients’ everyday lives than traditional clinical protocols ever could,” explains Dr. Alexander Nave, senior physician and project lead at Charité.
Participants wear sensors that track steps, heart rate, and sleep quality. They also respond to questions about their well-being and therapy experience—whether at home or in the clinic, directly via their smartphones. “We can instantly see if a smartwatch is being worn correctly or if data is missing. And we can intervene through the app—without needing the patient to return to Charité,” says Dr. Nave. For the first time, the Sensor-S Study is exploring correlations between mobility, blood sugar, and patient-reported data, with the goal of enabling personalized home-based therapies.
Daily behavior becomes a valid data source. And researchers can now test new, data-driven hypotheses, like: Does a stable glucose level extend walking distance during rehab? Could rising skin temperature throughout the day signal early signs of depression? How does reduced evening activity impact sleep quality or depressive symptoms? Until now, such questions were considered too everyday, too granular, too data-heavy to investigate.
The app enabling all of this is D4L Collect—originally developed in a research project led by renowned medical informatician Prof. Bert Arnrich. A pioneer in sensor-based health data collection, Prof. Arnrich has been working on this technology since 2019 at the Hasso Plattner Institute in Potsdam. It has since been developed further by Data4Life, a nonprofit healthtech organization based in Potsdam.
The promise: a single platform for sensor-based studies that makes high-resolution real-world data accessible and privacy-compliant for research—from fitness trackers and smartwatches to continuous glucose monitors.
“With D4L Collect, we can now address research questions that were previously unthinkable—simply because the required data didn’t exist,” says Prof. Arnrich.
D4L Collect already supports a range of devices including Fitbit, Garmin, Polar, glucose monitors like Dexcom, pulse oximeter smartwatches, ECG patches, Bluetooth-enabled scales, smartphone sensors, and GPS.
The app is designed to be intuitive—even for people with little tech experience. Most importantly: the data belongs to the participants. They decide who sees what.
This creates new potential for larger studies: people who trust the technology and feel in control are more likely to participate.
The medical benefits are significant. The more granular the data, the better researchers can understand root causes, progression, and treatment effects. For example, connections between low blood sugar and hypertension, or respiratory patterns in long-COVID, become visible.
D4L Collect paves the way for truly individualized precision medicine—capable of reducing unnecessary hospital stays and lowering healthcare costs.
It also opens new research fields for rare diseases, where large study cohorts are difficult to recruit. And it enables long-term studies—spanning months or even years—without on-site appointments, paper-based protocols, or technical hurdles. The platform is open to partnerships with clinics, institutions, foundations, and industry.
“We’re looking for the visionaries,” says Arnrich. “The ones asking: What if we had the right data?”
The answer is simple: The world would be a healthier place.
Questions like these were nearly impossible to study until recently. But science and healthcare are now at a turning point—thanks to a digital solution that taps into something already present: the continuous data of daily life.
Millions of people wear smartwatches and fitness trackers every day—but their data rarely makes it to where it could have the biggest impact: research and healthcare. That’s starting to change. The goal is personalized medicine that is not only more efficient, but also fairer.
Each smartwatch or wearable medical device can generate tens of thousands—sometimes millions—of data points per person per day: heart rate, movement, sleep, respiration, skin temperature, and more. These data are now being collected in a joint study by Charité and Brandenburg Clinics—using a single platform. The aim: to explore how mobility and metabolic parameters affect rehabilitation outcomes after stroke.
“We combine wearable data with app-based questionnaires, which gives us a more complete picture of patients’ everyday lives than traditional clinical protocols ever could,” explains Dr. Alexander Nave, senior physician and project lead at Charité.
Participants wear sensors that track steps, heart rate, and sleep quality. They also respond to questions about their well-being and therapy experience—whether at home or in the clinic, directly via their smartphones. “We can instantly see if a smartwatch is being worn correctly or if data is missing. And we can intervene through the app—without needing the patient to return to Charité,” says Dr. Nave. For the first time, the Sensor-S Study is exploring correlations between mobility, blood sugar, and patient-reported data, with the goal of enabling personalized home-based therapies.
Daily behavior becomes a valid data source. And researchers can now test new, data-driven hypotheses, like: Does a stable glucose level extend walking distance during rehab? Could rising skin temperature throughout the day signal early signs of depression? How does reduced evening activity impact sleep quality or depressive symptoms? Until now, such questions were considered too everyday, too granular, too data-heavy to investigate.
The app enabling all of this is D4L Collect—originally developed in a research project led by renowned medical informatician Prof. Bert Arnrich. A pioneer in sensor-based health data collection, Prof. Arnrich has been working on this technology since 2019 at the Hasso Plattner Institute in Potsdam. It has since been developed further by Data4Life, a nonprofit healthtech organization based in Potsdam.
The promise: a single platform for sensor-based studies that makes high-resolution real-world data accessible and privacy-compliant for research—from fitness trackers and smartwatches to continuous glucose monitors.
“With D4L Collect, we can now address research questions that were previously unthinkable—simply because the required data didn’t exist,” says Prof. Arnrich.
D4L Collect already supports a range of devices including Fitbit, Garmin, Polar, glucose monitors like Dexcom, pulse oximeter smartwatches, ECG patches, Bluetooth-enabled scales, smartphone sensors, and GPS.
The app is designed to be intuitive—even for people with little tech experience. Most importantly: the data belongs to the participants. They decide who sees what.
This creates new potential for larger studies: people who trust the technology and feel in control are more likely to participate.
The medical benefits are significant. The more granular the data, the better researchers can understand root causes, progression, and treatment effects. For example, connections between low blood sugar and hypertension, or respiratory patterns in long-COVID, become visible.
D4L Collect paves the way for truly individualized precision medicine—capable of reducing unnecessary hospital stays and lowering healthcare costs.
It also opens new research fields for rare diseases, where large study cohorts are difficult to recruit. And it enables long-term studies—spanning months or even years—without on-site appointments, paper-based protocols, or technical hurdles. The platform is open to partnerships with clinics, institutions, foundations, and industry.
“We’re looking for the visionaries,” says Arnrich. “The ones asking: What if we had the right data?”
The answer is simple: The world would be a healthier place.
