A plantar pressure analysis system is a high-tech device used to measure and evaluate the pressure distribution between the foot and the supporting surface during standing or walking. Its core principle involves collecting pressure data from various regions of the sole using a high-density sensor array, and then conducting visual analysis and biomechanical assessment through software algorithms.
Below is a detailed breakdown of its working principles:
I. Basic Components
A typical plantar pressure analysis system usually consists of three parts:
- Pressure Sensing Platform or Insole: Embedded with numerous miniature pressure sensors to collect plantar pressure data.
- Data Acquisition and Transmission Module: Converts sensor signals into digital information and transmits it to a computer or mobile device.
- Analysis Software: Processes, models, and visualizes the collected data, generating diagnostic reports.
II. Core Technical Principles
1. Pressure Sensing Technology
The system uses highly sensitive piezoresistive or capacitive sensor arrays (common in platform-based devices) or flexible thin-film sensors (common in insole-based devices). When pressure is applied to the sole:
- Piezoresistive sensors: Their resistance changes in response to pressure.
- Capacitive sensors: The distance between two conductive plates changes under pressure, altering the capacitance.
These physical changes are converted into electrical signals, which are then transformed via analog-to-digital conversion into readable digital pressure data.
2. Spatial Resolution and Sampling Frequency
- Spatial Resolution: Refers to the number of sensors per unit area (e.g., sensors per square centimeter), determining the detail level of the pressure distribution map.
- Temporal Resolution (Sampling Frequency): Typically ranges from 50Hz to 500Hz, meaning 50 to 500 data frames are captured per second, ensuring dynamic changes during the gait cycle (e.g., heel strike, toe-off) are accurately recorded.
3. Data Acquisition Modes
- Static Testing: The subject stands naturally on the platform to measure pressure distribution, center of gravity, and left-right balance in a stationary state.
- Dynamic Testing: The subject walks or runs across the pressure platform, and the system continuously records the plantar pressure changes throughout the entire gait cycle, generating “pressure footprint maps” or “pressure-time curves.”
4. Software Analysis and Modeling
Raw data is processed through specialized algorithms to generate various analytical results:
- Pressure Distribution Heatmaps: Use color coding to visually display high-pressure areas (red) and low-pressure areas (blue).
- Center of Pressure (COP) Trajectory: Reflects the path of body weight center movement during standing or walking, used to assess balance.
- Regional Pressure Statistics: Divides the foot into areas (forefoot, midfoot, hindfoot, arch, etc.) and calculates parameters such as peak pressure, total pressure, and contact area for each region.
- Gait Cycle Analysis: Breaks down gait phases (e.g., stance phase, swing phase) and analyzes time distribution and pressure trends in each phase.
III. Application Areas
Based on the above principles, plantar pressure analysis systems are widely used in:
- Medical Rehabilitation: Diagnosing flat feet, high arches, diabetic foot, plantar fasciitis; postoperative rehabilitation assessment.
- Sports Science: Optimizing athletes’ running form, preventing sports injuries, customizing orthotic insoles.
- Orthotics and Footwear Design: Personalized design of insoles, athletic shoes, and prosthetic sockets.
- Elderly Fall Risk Assessment: Evaluating fall risk based on balance and gait stability.
