A revolutionary wearable sensor that tracks muscle and joint movements

Most motion trackers are based on IMUs capable of 9-axis tracking. However, IMU-only trackers cannot accurately measure the activity of muscles and joints, which are the core of exercise, and require an unnecessarily many sensors for measurement, which is cumbersome and expensive.

Fitness tracking is NOT just motion tracking. The Keefit team has developed an innovative tracker optimized for exercise from an exercise mechanics point of view. The Keefit Sensor integrates a 9-axis IMU sensor with patented technology that accurately measures contraction-relaxation of joints and muscles, allowing you to track your workouts effectively and efficiently at minimal cost. Keefit is the world's first and the only system that can accurately measure arm or leg movement with just one sensor. Keefit Sensor is made of thin and flexible silicone material, so the user does not feel discomfort even with vigorous exercise.

The 9-axis IMU inherent in the Keefit Sensor uses a state-of-the-art chip from a global lead manufacturer to provide the highest level of tracking quality in existence. Please refer to the Appendix at the bottom of the page for detailed tracking quality.

A beautiful fitness tracker as a fashion

Another challenge that a fitness tracker has to solve is beauty. Keefit Sensor provides a beautiful design to be used as a fashion item. In addition, it can be used with the elbow and knee braces that many people are familiar with, so it is comfortable without being burdensome in appearance.

The most affordable price, $25 at the lowest, literally for everyone

Keefit provides the world's lowest price, so anyone can use Fitness Tracker without worries. We offer a 4-piece set that can track all your arm and leg movements for $99. For more details, please refer to the price plan, which will be updated later.

Students or engineers researching IMU-based motion tracking can also develop their fitness software using the Keefit Sensor. See the Ecosystem page for details.

Combine your heart-tracking device for better experiences

Heart rate measurement is the most basic of Fitness Tracking. Keefit supports real-time tracking of heart rate data through linkage with the Apple Watch. In the future, almost all heart rate trackers on the market will also be supported quickly.

Appendix. Hardware Specifications

CPU Nordic nRF52832-QFAA With BLE
Operating frequency range 2401 - 2480 MHz / Bluetooth 5.0
Antenna Chip Type
Interface Button X 1
USB-C For Charging Only X 1
Accelerometer + Gyroscope BMI323
Magnetometer Bosch BMM150
Battery Li-Polymer 3.7V 302030 130mAh
IP Rating IP67~8
Dimension TBD
Weight TBD
Working Temperature -0 ~+40 °C
Storage Temperature -20 ~+60 °C
Environmental humidity range 20-80%

Appendix.1 Keefit Sensor Spec. - Gyroscope Capacity

Spec. Unit Value
1 Standard full range [°/s] ±2000
2 Sensitivity [LSB/g] 16.4
3 In-run bias stability [°/h] 10
4 Bandwidth (-3dB) [Hz] 255
5 Output noise density [°/s/√Hz] 0.007
6 g-sensitivity [°/s/g] 0.1
7 Nonlinearity [%FS] 0.1
8 Scale factor variation [%] 0.5 (typical) / 1.5 (over life)
9 Sample Frequency [Hz] 800
10 Resolution [bit] 16

Appendix.2 Keefit Sensor Spec. - Accelerometer Capacity

Spec. Unit Value
1 Standard full range [g] ±16
2 Sensitivity [LSB/g] 2048
3 In-run bias stability [mg] 0.03
4 Bandwidth (-3dB) [Hz] 324 (Z axis: 262)
5 Output noise density [µg/√Hz] 120
6 Nonlinearity [%FS] ±0.5
7 Sample Frequency [Hz] 800
8 Resolution [bit] 16

Appendix.3 Keefit Sensor Spec. - Magnetometer Capacity

Spec. Unit Value
1 Full scale [Gauss] ±8
2 Total RMS noise [mGauss] 0.5
3 Resolution [mGauss] 0.25
4 Nonlinearity [%FS] 0.2
5 Sample Frequency [Hz] 60
6 Resolution [bit] 16