Of those impacted by period poverty, many reside in low-resource and/or remote areas. Geographically, they are cut off from many of the supply chains that supply necessary health products such as disposable menstrual pads. And often, even if these products do reach the shelves, they are extremely expensive or are low-quality and produce a ton of plastic waste.

To better understand this challenge, we need to first understand the critical components of a pad.  When we look at menstrual pads in general, we typically find three main layers: (1) top porous layer - this is the layer that is in direct contact and keeps the top feeling dry against the skin via fast wicking, (2) middle absorbent layer - this is the bulk of what absorbs and retains the blood, and (3) bottom non-porous layer - this is the final layer of the pad that typically is adhered to the garment and prevents blood from leaking out of the pad.

Although so far we’ve only really explored sisal, the hope is that what we learn from sisal can be applicable to other plants that are readily available in other parts of the world. So far we’ve preliminarily tested flax and hemp for the middle layer and both have shown promising results.

Stay tuned for more updates!

While researching, we came across many groups that were already trying to produce absorbent materials using plants. Some of these included banana pseudostem, bamboo, and jute. Coincidentally, we had a connection in Kenya, Alex Odundo, who builds decorticators and works with farmers growing sisal in the Kisumu area. Sisal is a succulent, easily grown in semi-arid areas, and are usually harvested for their fibers for use in industrial ropes. Sisal leaves are typically decorticated to strip off the plant tissues off of the fibers, after which fibers are thoroughly washed and dried in the sun. Because not much has been studied on sisal for the purposes of absorbent media and having direct access to the materials, we decided to start our studies with sisal. It was important for our work that we sourced the fibers directly from the farmers to ensure that the fibers we were working with were raw and no additional treatment (aside from being extracted using the decorticator).

So now that we have demonstrated how sisal fibers can be mildly treated to produce absorbent fluff meeting that of cotton, we now need to apply a similar approach to produce materials of “opposite” properties for the top and bottom layers. While for the middle layer we were mainly focused on extracting the cellulose fibers and removing the lignin, for these other two layers, we need to extract and collect the lignin. Lignin has a hydrophobic nature and, to some degree, can polymerize to form a continuous hydrophobic sheet.

We have just started on this effort and have successfully extracted lignin from sisal using a deep eutectic solvent. The next challenge is to be able to cast and form these sheets that are not only hydrophobic but also flexible and has some elastic strength to prevent rupture. So far, we have produced small sheets using the extracted lignin from sisal that are either double-sided hydrophobic (for the bottom layer) or single-sided hydrophobic (for the top layer). While the bottom layer should not allow liquid to penetrate up or down through it, the top layer needs to still wick on one side while prevent absorbed liquid to penetrate back up. We are currently working on developing uniformity, consistency (across batches), and strength within these sheets.