Recent Progress on Skin-Compatible Flexible Photoplethysmography Sensor

Photoplethysmography (PPG) sensors, which utilize light to detect blood volume changes in the skin, offer advantages over traditional methods by being non-contact, avoiding electrical stimulation, and integrating seamlessly with wearable devices. However, conventional PPG sensors are primarily composed of rigid, inorganic materials, limiting their flexibility and causing discomfort during prolonged use. To overcome these challenges, recent research has focused on flexible PPG sensors using organic, perovskite-based, and other stretchable materials. These sensors exhibit improved mechanical adaptability, biocompatibility, and comfort while maintaining high accuracy in detecting vital signs such as heart rate and oxygen saturation levels. This review demonstrates recent progress in the materials and fabrication techniques for flexible PPG sensors, emphasizing the potential of these devices for long-term, real-time health monitoring in everyday applications