SmartStep: A Fully Integrated, Low-Power Insole Monitor

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Sensor Systems

Background:

• Shoe-mounted wearable sensors are valuable for activity monitoring, gait analysis, and rehabilitation.
• Existing sensors often require shoe modification, limiting widespread adoption.
• A need exists for unobtrusive, versatile wearable sensors compatible with various footwear.

Purpose of the Study:

• To develop and evaluate SmartStep, an insole-based wearable sensor system.
• To address the limitations of shoe-mounted sensors by eliminating the need for shoe alteration.
• To demonstrate the feasibility of a low-power, reliable insole sensor for continuous monitoring.

Main Methods:

• Integration of a 3D accelerometer, 3D gyroscope, and pressure sensors into a generic insole.
• Utilizing a CC2540 system-on-chip with an 8051 processor, Bluetooth low energy (BLE), and flash memory.
• Development of low-power strategies and a robust data buffering method for intermittent connectivity.
• Wireless interfacing with an Android smartphone application for data logging and visualization.

Main Results:

• SmartStep demonstrated a power consumption allowing for over two days of continuous wear between recharges.
• Mechanical reliability tests confirmed the durability of pressure sensors under prolonged human use.
• The system achieved over 98.5% data collection accuracy in real-world scenarios with intermittent connectivity.

Conclusions:

• SmartStep provides a practical, non-invasive solution for wearable sensing in diverse footwear.
• The system offers a reliable and low-power platform for various applications, including activity monitoring and rehabilitation.
• SmartStep's design effectively manages data buffering and low-power requirements for extended use.