Flexible Pressure Sensors and Machine Learning Algorithms for Human Walking Phase Monitoring

Abstract

Soft sensors are attracting much attention from researchers worldwide due to their versatility in practical projects. There are already many applications of soft sensors in aspects of life, consisting of human-robot interfaces, flexible electronics, medical monitoring, and healthcare. However, most of these studies have focused on a specific area, such as fabrication, data analysis, or experimentation. This approach can lead to challenges regarding the reliability, accuracy, or connectivity of the components. Therefore, there is a pressing need to consider the sensor’s placement in an overall system and find ways to maximize the efficiency of such flexible sensors. This paper proposes a fabrication method for soft capacitive pressure sensors with spacer fabric, conductive inks, and encapsulation glue. The sensor exhibits a good sensitivity of 0.04 kPa−1, a fast recovery time of 7 milliseconds, and stability of 10,000 cycles. We also evaluate how to connect the sensor to other traditional sensors or hardware components. Some machine learning models are applied to these built-in soft sensors. As expected, the embedded wearables achieve a high accuracy of 96% when recognizing human walking phases.

Flexible and Stretchable Pressure Sensors: From Basic Principles to State-of-the-Art Applications

“…Additionally, the integration of artificial intelligence and machine learning algorithms can enable real-time data analysis, pattern recognition, and predictive modeling, leading to advanced monitoring and diagnostic capabilities [ 160 , 161 ]. Future applications include personalized healthcare [ 162 ], sports and fitness monitoring [ 163 ], virtual and augmented reality interfaces, human–robot collaboration, and intelligent wearable devices. Researchers are also exploring novel integration approaches, such as 3D printing or textile-based integration, to expand the possibilities and versatility of flexible and stretchable pressure sensors.…”

Ultrafast piezocapacitive soft pressure sensors with over 10 kHz bandwidth via bonded microstructured interfaces

“…This limitation seems to be unreconcilable as long as viscoelastic materials are used and interfacial gaps persist. Although there are a few very recent advances reporting sensors with a shorter response-relaxation time down to a few milliseconds 6 , 24 – 26 , such sensors can still not be used to detect high-frequency vibrations of hundreds or thousands of hertz, and thus the application of the sensors to high-frequency or acoustic purpose is still unavailable.…”