Design and fabrication of nepenthes alata-inspired sweat collection patch using wettability patterning method

Sweat-based wearable devices are attracting attention for non-invasive monitoring of various biomarkers present in sweat. However, the problem of inadequate sweat volume remains prevalent in sweat testing. To overcome this challenge, we present an integrated flexible platform that incorporates open microfluidic tracks, specifically designed for efficient sweat collection. The construction of these tracks involves employing a simple wettability patterning method using PDMS-TiO2 nanocomposite as a coating surface. Additionally, a thorough characterization study is conducted to analyze the synthesized composite material comprehensively. Furthermore, we propose a novel curvilinear wedge track design, inspired by the teeth structure of Nepenthes alata, to enhance droplet collection, achieving an improvement in collection efficiency in the range 86–94%. The physics of droplet transport is explained through simulations. To demonstrate the feasibility of our approach, we fabricated and tested a patch embedded with a wedge track and a screen printed three-electrode system, showcasing successful sweat collection. The novelty of this work lies in the development of a fabricated patch that minimizes sample volume requirements when integrated with the electrode system. Additionally, its orientation-independent design makes it suitable for wearable applications.