Tutorial

If you'd like to know exactly how to recreate our project, you've come to the right page. The following tutorial and video will show you exactly how to make each layer of our hydrogel wound dressing.

Materials:

1. Food-grade sodium alginate, 9.0 g

2. Pure water, 200 mL

3. 150-mL glass beakers, 3

4. Soap mold with at least 2 8 x 7.1 x 1 inch compartments, 1

5. 30% calcium chloride solution, at least 15 mL

6. Self-adherent medical wrap, 2 x 12 inches

Procedure:

Mixing the alginate solution:

1. Add 2.0 g of food-grade sodium alginate to 100 mL of pure water. Mix thoroughly. There may be chunks of alginate that are difficult to dissolve, but after mixing for several minutes the solution should have a uniform consistency with no chunks.
2. In a separate beaker, mix 7.0 g of sodium alginate with 100 mL of pure water. This solution will be even harder to mix properly, so it is best to add the sodium alginate in small amounts.
3. Add food dye to these solutions if desired.

Preparing the calcium chloride:

4. Add 5 mL of 30% calcium chloride solution to 25 mL of water. This will make 30 mL of 5% calcium chloride solution. This will likely not be enough to create the entire wound dressing, so make more of this solution as needed. 

Making the gel:

5. Pour the alginate solutions prepared in steps 1 & 2 into separate compartments of a soap mold. The gel prepared in step 2 will be especially viscous, so it will need to be smashed down with an instrument such as a spoon. Pour enough so that it covers the bottom of the compartment. The solution prepared in step 1 should be about half the thickness of the solution prepared in step 2.

6. Pour enough calcium chloride over each solution so that there is a thin layer covering each solution. The solution should form a gel upon contact with the calcium chloride, but allow it to sit for a few minutes to make certain that the solution has completely gelled. 

Putting together the prototype: 

7. Remove the gels from the soap mold, and combine. The 7% alginate hydrogel (from the solution in step 2) should be in placed in contact with a long strip of the medical wrap (about 10 inches), with the 2% alginate hydrogel (from the solution prepared in step 1) should be placed on top of the 7% layer. 

8. Thin strips of the self-adherent wrap should be cut and placed across the double-layered hydrogel on opposite sides, securing it to the bandage.

See the video below for a demonstration of steps 5 and 6. This demonstration shows the formation of the thick, high-density layer of hydrogel made from 7% sodium alginate solution (prepared in step 2).