Flow Manipulation in Thread-Based Microfluidics by Tuning the Wettability of Wool

Recent progress in thread-based microfluidic devices has provided portable and inexpensive field-based technologies enabling medical diagnostics, environmental monitoring, and food safety analysis. However, capillary-driven liquid flow in a single thread, a crucial aspect of thread-based microfluidics, is difficult to control. Among potential materials, hydrophobic wool thread is an appropriate candidate for liquid flow control in thread-based microfluidics because its wettability can be readily tuned by the introduction of a natural color pigment, thereby manipulating flow. Thus, utilizing natural wool thread as a channel, we demonstrate here that liquid flow manipulations, such as microselecting and micromixing, can be achieved by coating the complex Al(III) (Alum) brazilein onto wool thread. In addition to enabling flow control, the coated wool channels consisting entirely of naturally occurring substances will be beneficial for biological sensing devices.