Engineering Lecture: Designer Biomaterials

Today, I went to the lecture by Dr. Anita Shukla of Brown University, who is starting her biomedical engineering lab there. I really enjoyed the lecture, especially as a student who is interested in the biological sciences (although I'm not a science major). During her fascinating lecture, Dr. Shukla talked about her various projects involving drug delivery for traumatic injuries, controlling the delivery of antibiotics, pain relievers, and hemostatic dressings. It was really interesting to hear about her thought processes for the projects - the different obstacles she had to consider when designing the bandages, such as drug-resistant bacterias, assembly techniques, and the positive and negative aspects of each design. On the simplest level, Dr. Shukla's lecture connected to our class because we too have to design things (although not at the cellular level) and consider and critique various aspects of our designs.

Stove: Part III

Our finished prototype!

bottom view with legs and air vents

Isabella demonstrates the fuel drawer

front view of the fuel drawer

Our stove held up pretty well during the test. The chimney worked, and we did see smoke coming out of it. The drawers and different parts of the stove functioned as we intended, and the water was heated a little bit, although it did not reach a boil. The charcoal cooled down quickly after the fire started were all burned up, and we attributed this to an inadequate amount of air flow to the fuel drawer. Overall, we were happy with our results, but we wished that the charcoal had heated the water more effectively. Given that, we would change at least two aspects of the design. We would decrease the space between the charcoal and heating surface, as we saw how groups with a shorter distance between these parts were able to heat their water to higher temperatures. We would also increase the flow of air to the fuel drawer in order for there to be more oxygen and combustion.

The water reached the highest temperature, 43.5 degrees Celsius, after 5 minutes of heating.

Stove: Part II

Building the stove out of aluminum sheet metal was both easier and more difficult than we had expected. Who knew that you could rip metal with your bare hands?!

After scoring the aluminum sheet with a
 blade, it was easy to take apart by hand.

We started out by drawing our plans on different pieces of metal, so that we would be able to fold the sheet over and form the box, rather than rivet six pieces together. This had its own set of pros and cons: it required less riveting, but was tricky to rivet pieces together when the box was built.

Drawing out the plans for the box part of the stove.

I did not find it difficult to keep in mind our vision for the final prototype while drawing out plans, but the materials used presented their own set of challenges. Sheet metal is very different from foam core and cardboard, materials that I am more accustomed to working with, but as the building process went on, I adjusted my expectations of what the material could do. Bending a sheet of metal twice and trying to rivet small parts together turned out not to be so feasible. The smaller parts of the stove legs, which were designed by Katie and worked wonderfully in cardboard, broke off when I tried to rivet them in place. Sadly, I'm not Rosie the Riveter.

Having a large group of five for one project seemed like a lot at first, but we made it work for us by assigning different parts to everyone. After several hours spent working on Tuesday, it was such a thrill to have a closed container of some sort!

Cutting air vents on the bottom of the box part.

Cutting out the fuel box

Stove: Part I

Our group started out by brainstorming, and we came up with a variety of ideas, including a stove with a hood, a chimney, in a box form, with drawers, and ones with various levels from the heat source.

 We didn't really make a Pugh chart; instead, we combined our favorite ideas from each of the designs, to create a stove with a flat cooking surface, chimney, closed box with a drawer for fuel, and a divider inside the box that would keep most of the heat to one side of the box, so that the different sides of the stove would have different heats (low and high). The divider can be removed so that both sides of the stove can be used for high heat cooking.

Personal daily energy consumption log (approximate)

I calculated the energy consumption for all usage that I had some control over - turning on lights, doing laundry, etc. I didn't factor in energy consumption for times that I was out of my room (in the dining halls, in class, in the library), so increasing my calculations by around 100 Watts would probably be more accurate.

For most of the values, I looked at the labels on my appliances. My minifridge, for example, listed the current and voltage as 1.4A and 115 V, so I could then calculate the power used from there. I also found an extremely handy site from the government, Estimating Appliance and Home Electronic Energy Use, which lists the average power for most appliances. For calculating the energy I used on the elliptical at the gym, I did some research and found this article on Slate.com, where it states that "On average, a treadmill uses between 600 and 700 watts of energy....But even at maximum resistance, [ellipticals] require six to seven times less energy than treadmills." I'm sure that there were some things I forgot to record in my list of times that I used electricity, but I think this goes to show how much we don't even think about the amount of energy we use everyday.

Power Estimations

Water Challenge

Full disclosure: I tried the water challenge for one day, with minor adjustments to fit my routine. On Saturday, I made an effort to go to the bathroom in another dorm, and showered at the sports center. I tried to stay out of my dorm for most of the day because that would reduce the chances that I'd want to go to the bathroom while in my dorm building. Sunday, I was out of underwear and had to do my laundry, so that was the end of the water challenge for me.

Writing this now, I feel like a stuck-up whiny princess. But although I didn't participate fully in the challenge, even for that one day I became more aware of how frustrating and time-consuming getting water can be. Setting aside time in my schedule, or knowing that a bathroom break could take about five minutes from my study time was hard, but it made me appreciate that life here at Wellesley is really easy compared to other parts of the world. I can see how the process of getting water in developing countries is a daily struggle. And not to mention that the water in those places isn't always potable or safe to drink. I have taken bucket showers and used pit latrines while traveling through India with my family, and stayed with relatives who have a water tank in the bathroom  and boil water every morning. Water is a necessity, but unfortunately it is a luxury for so many people.