Lab-on-leaf: Bioimprinted zein films and natural microfluidics for integrated photonic sensing

On-site biosensing applications present challenges in sample handling, miniaturization, and automation. Microfluidic technology has emerged as a key enabler, offering precise fluid control that enhances reaction efficiency and scalability. At the same time, the reliance on synthetic materials raises concerns regarding sustainability and environmental impact. These challenges can be addressed through the integration of natural biopolymers, which offer renewable alternatives for developing eco-friendly sensing platforms. This work presents two novel bioinspired proof-of-concept platforms that integrate photonic transduction into natural microfluidic structures, using leaf vein patterns as channel templates due to their inherent efficiency in fluid transport. The first approach uses zein film-based microfluidic platforms. The toxicity of these films was assessed using zebrafish embryos, showing no significant adverse effects. These results suggest that zein-based films are a safe and sustainable option for sensor development, with minimal environmental and biological impact. Next, zein films were bioimprinted with the vasculature of leaves, forming a microfluidic system, followed by the assembly of a photonic structure at the detection zones. In the second approach, the natural microfluidic architecture of leaves was harnessed through decellularization, using the vascular network to transport fluids to photonic sensing areas. This study establishes the foundation for lab-on-leaf devices, where renewable materials and bioinspired architectures converge to create sustainable microfluidic platforms. Beyond advancing the fundamental understanding of biopolymer-based microfluidics, these approaches open pathways toward next-generation, eco-friendly sensing technologies. • Zein films are non-toxic and can be used as sustainable sensing platforms. • Bioimprinting leaf vasculature on zein films forms bioinspired microfluidic networks. • Decellularized leaf veins are natural channels directing fluid to detection sites. • Lab-on-leaf devices combine structural color with natural and zein microfluidics.