Prototyping

We have tested multiple wick lengths and possible sticker designs. Having the wick divide into lanes, each containing a different biochemical test proved to be very efficient.

The picture on the left is such an example. The right most lane contain Griess reagent which detect the presence of nitrites (pink/yellow). The left most lane contains pH paper. The wick was placed inside an Eppendorf tube containing approximately 1mM NaNO2 and blue dye. It took about 20min for the solution to reach the sticker through a 10cm long heath shrink insulated wick. Wicking continues even after solution has run along the wick due to absorbent pad in the sticker.

Additionally, we tested the wicking properties of our cotton thread if instead of being place in direct contact with liquid, it was placed in contact with a moist calcium alginate dressing. Our experiments show that, though slower, the cotton thread is still able to wick liquid from the most membrane.

We ran this experiment after our reviewers voiced concerns about our initial prototype where a wet gauze (or cotton) would be place at the vicinity of the entry point (needle) to act as the source of moist where the cotton thread could wick from. As it turns out, bacteria are fond of dark, humid, environments and this aspect of our device could potentially cause IV infections. We are considering making use of the alginate dressings to overcome this limitation, though further experiments are necessary.

-Thais