Highly sensitive PDMS-Ag nanoflakes porous pressure sensors prepared by templating and molding approaches for wearable applications

The rise of information technologies has led to the need for collecting vast amounts of multidisciplinary data related to human habits, social interactions, and physical activities. This demand has intensified the challenge of integrating rigid electronics with the flexibility of human tissue. Wearable sensors have emerged as a solution to detect several biometric signals from human body. Among these applications, pressure sensing is particularly crucial. In this work, we present a flexible, sandwich-structured pressure sensor based on a porous PDMS sponge. Two distinct fabrication methods were investigated with a critical analysis of their advantages and limitations. A templating technique using a common sugar cube as a sacrificial mold, and a molding method where a sugar-PDMS slurry was shaped using a predefined mold. While the templating approach offers simplicity and accessibility, the molding method provides greater control over geometry and customization. All fabricated sensors demonstrated excellent piezocapacitive performance under mechanical compression, characterized by minimal hysteresis during cyclic loading—an essential feature for consistent and reliable sensing. To boost sensitivity, silver nanoflakes were incorporated into the polymer matrix, resulting in a 65 % increase in pressure sensitivity, achieving up to 0.047 kPa⁻¹ , one of the highest value reached by PDMS-based foam sensors, and lowering the detection threshold to just 0.6 g (40 Pa). The successful implementation of these sensors in wearable formats underscores their potential as lightweight, scalable, and cost-effective platforms for continuous biometric monitoring in real-world applications.