Image source: Fitbit

Fitbit’s ‘Fit Score’: A patent that ensures your wearable fits right

Fitbit’s patent, US 11,850,071 B1, granted on December 26, 2023, outlines a sophisticated system designed to enhance the accuracy and reliability of data collected by wearable devices. It describes an innovative approach to monitoring and adjusting the fit of these devices on the user’s body.

This innovation is important in an industry where, according to a 2022 survey by Pew Research Center, 21% of Americans regularly use a smartwatch or fitness tracker. However, a significant challenge with these devices is ensuring an accurate fit, which is crucial for reliable data collection. A study in the Journal of Personalized Medicine (2021) highlighted that an incorrect fit could lead to errors in heart rate monitoring by up to 20%. Fitbit’s patent aims to address this gap, ensuring that users get the most accurate data from their devices.

Fitbit’s solution: Active monitoring of fit

Traditional wearable devices do not actively monitor how well they fit against the user’s skin. Fitbit’s patent introduces a solution to this by characterizing the forces at the surfaces where data is measured.

The patent describes a system that continuously monitors the forces acting on the housing of the wearable device. This monitoring allows the device to assess the interface between the skin sensors and the skin itself. By doing so, the device can determine if it is seated properly on the user’s body. This is crucial for sensors that require consistent contact with the skin. For example, optical sensors used in heart rate monitoring and photoplethysmography (PPG) sensors.

An important aspect of this technology is its ability to adapt to changes in the fit of the device. As the user engages in different activities, the position and tightness of the wearable can change, affecting sensor readings. Fitbit’s system can dynamically respond to these changes. It adjusts the readings or alerts the user to reposition the device for optimal data collection.

The patent also details how the wearable device can calibrate data based on the fit. If the device detects that it is fitted too loosely or too tightly, it can adjust the data it collects to account for these variations. This calibration ensures that the physiological data remains accurate despite changes in the device’s positioning or pressure against the skin.

A key feature of this technology is the ability to notify users when the device is not seated correctly. This immediate feedback can prompt users to adjust the fit of their device, ensuring continuous and accurate monitoring of their physiological data.

Fitbit fit patent

Enhancing user experience and safety

Beyond accuracy, Fitbit’s innovation is about user safety. A study in the Journal of Sports Sciences in 2019 indicated that 15% of wearable device users experienced skin irritation due to improper fit. In our experience, this percentage is probably even higher. By ensuring optimal fit, Fitbit’s technology not only enhances accuracy but also user comfort and safety.

Essential readingTop fitness trackers and health gadgets

Finally, Fitbit’s system is designed to adapt to changes in fit over time. This is important given that a user’s wrist diameter can vary by up to 5mm during different activities, as per a 2021 biomechanical study. This dynamic adjustment maintains accuracy across various activities and conditions.

We particularly like the ‘Fit Score’ feature shown in the images above. This innovative approach has the potential to provide a unique and effective method of informing users about the proper fit of the device on their wrist.

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Ivan Jovin

Ivan has been a tech journalist for over 7 years now, covering all kinds of technology issues. He is the guy who gets to dive deep into the latest wearable tech news.

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