Estudo da vazão de um sistema microfluídico com detecção amperométrica: influência dos fios têxteis

Abstract

Textile thread-based analytical microfluidic devices have received considerable attention recently due to their low cost, ease of fabrication, low consumption of chemicals and samples, and low generation of waste. In these devices, fluids are passively transported due to the capillary action provided by the microchannels formed by the voids between the fibers of the threads. Therefore, thread-based analytical microfluidic devices do not require pumps to drive the fluids through the microchannels making their assembly easier and inexpensive. Despite being promising devices, some challenges are still present regarding the designing and fabrication of thread-based analytical microfluidic devices. Major challenges include achieving high and stable flow rates for long times and to understand the mechanisms of fluid transportation in different textile threads. In this context, the objective of this study was to evaluate the transport of aqueous solutions in different textile threads by measuring the flow rates of aqueous food coloring solutions. The following textile threads were evaluated: raw cotton string generally used for craft, polyester, and hydrophilic gauze threads. These threads were subjected to different pretreatments involving the washing which ultrapure water and sodium carbonate solution. The threads with the best fluid transport properties were inserted in an amperometric thread-based microfluidic device previously developed in our research group. The amperometric response for ferrocyanide ion was evaluated with these threads. The obtained results have shown that the polyester thread provided the highest flow rates regardless of the pretreatment, but the precision obtained with this thread was low. All the pretreatments studied decreased the flow rate for hydrophilic gauze compared to untreated gauze threads. For the raw cotton string, the pretreatment with ultrapure was the most adequate to ensure high and repetitive flow rates. The untreated cotton string thread was unable to transport fluids and the pretreatment with sodium carbonate solution lowered the flow rate for this thread. The amperometric studies have shown that the cotton string threads treated with ultrapure water displayed the highest amperometric response for ferrocyanide ion and the higher precision, indicating that these threads are the most promising to develop novel electrochemical microfluidic analytical devices.