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.

WaterWear Backpack response

From reading the article posted to the course Google Site, it sounds like the WaterWear backpack was developed by people at companies, as a safer and easier way to carry water. It seems like a pretty simple idea - to have a backpack filled with water.

Some pros:

-Keeps water away from the ground (no encounters with puddles/dirt)

-New materials: not a used oil/chemical container

-Seems easier than carrying water on top of your head

-Hands-free

Some cons/questions:

-Only holds a small volume of water

-How do you clean this?

-Is it expensive to buy/produce?

-Does it break/tear easily?

If I had $10,000 to spend, I would maybe spend some money on distributing this, but not all. If I had that kind of money, I would spend a major portion working to create infrastructure and a safer and more accessible water system, so that the water source would be closer to where people live. Making the water more easily accessible would remove the need for women and girls to make day-long trips to water; instead, they could make shorter trips to the well.

Gravity Light - is this legit?

The concept of the gravity light is a really great idea - but I'm very skeptical of it. Converting gravitational potential energy into light energy is definitely feasible, but you would probably need a HUGE mass to achieve LED light for 30 minutes. I did some very sketchy calculations, using the formula for gravitational potential energy and basing it on the LED we used in class (3.2 V, 20mA). 

For my estimate, I did look up a few things on Wolfram|Alpha, which is really a magical place of numbers and information (http://www.wolframalpha.com/). According to that, a 1 kg weight at a height of 10 meters has a potential energy of 100 Joules. I also guessed that maybe 5 LEDs would be in the Gravity Light.

After squishing the data together and some head scratching, I estimate that the weight needed to work the Gravity Light will be huge. The number I ended up with is 186 million kg, which is impossible and most definitely  not a viable option.

So I am going to estimate, based on the fact that those bags in the Gravity Light video were not that large, that the weight required to work the Gravity Light for 30 minutes is 10 kg. Assuming that the weight required is not more than a person (~50 kg), this is a viable option.

WATER: Reflections on the 2006 UN Human Development Report

The readings from the 2006 UN Human Development Report on water were really eye-opening. The facts that struck me the most were that the poorest people pay the most for clean water, and that women and girls are not allowed to go to school because of a lack of private toilets. I was surprised - but unfortunately not all that surprised - at the practices of people who live in areas where there is no access to sanitation. I think it's incredible that the world can in fact implement clean water and access to sanitation by 2015 - that's so soon, and from the Youth Booklet, it sounds like it is a realistic goal. Although part of me is cynical about this, I hope that this will become reality.

It's clear that everyone needs to work together on making sure that all the people have access to water. Policies need to be drastically changed. Some countries are giving far more help than others. Why aren't we putting all our effort and money towards this, instead of financing wars and weapons? Everyone will benefit from clean water, and nobody benefits from war.

Project 2: Sharps Dispenser

Goal: to design and build a sharps dispenser for cutting blades, that will contain blades used in L024 and can be thrown away with the garbage.

My group members and I started by brainstorming many ideas, including mechanisms that would roll the blades in paper and a foam box with a hole in it. Eventually, we decided on a foam box which would make it nearly impossible for sharp blades to fall out of it because of a folded piece of cardboard, which would block the slit in the case that the container was tipped over. Surprisingly, the initial sketch was pretty similar to what we ended up building.

Foam-lined box with slit

The blade would be wrapped in paper and dropped into a box - not the most feasible idea.

The sketch we chose to work with.

Finding materials and deciding what the box would be made of was actually not that bad. I knew that there was a bin of throwaway foam outside, and we found a foam box (with lid!). We cut a hole in the lid, and measured a piece of cardboard to put inside the box. We didn't have to glue the cardboard in the box because it fits in tightly to two sides of the box. The other two sides of the cardboard create gaps with the foam box for the blades to fall under.

The cardboard triangle, with two sides for the blades to fall through.

Towards the end of class, we decided that we should probably test out the box, to see if it actually worked. And it does! One of my group members dropped in part of a blade, shook around the box, even turning it upside down. The blade stayed in the box, and was trapped beneath the cardboard triangle. Excellent!

The next thing to do was to decorate the box so that it would look like a sharps container. Unfortunately, my two group members from the first day of class did not return, but my new partner Isabella and I chose to cover the container with red construction paper and orange triangles, to denote that this was 1) a box for dangerous things that are 2) sharp (hence the triangles). Additionally, we cut out two orange triangles, which point towards the opening of the box.

Isabella with the finished product!

Project 1: Turn all the lights on!

Goal: to design a lantern that will work and maximize light in a classroom setting.

I started out this project by thinking about some possibilities for the shape of the lantern. I decided to use a plastic water bottle to hold the circuit, because it would be easy to hold, and then the bottom of the bottle could function to disperse the light. After several sketches, I realized that it would be better to have a reflective surface between the LED and circuit, so that the light would reflect and there would be twice as much light. After a few days of searching for good materials, I still had not found the reflective surface (a CD) that I wanted, so I adjusted the design of the lantern.

I started out by building a simple circuit, consisting of a 9V battery, tin foil slivers for wires, a 3.2V LED, and a 270 Ohm resistor (a 290 Ohm resistor would have been ideal, but that was not available, so I chose the resistor that was a size smaller. I figured that a 300 Ohm resistor would not work as well as the 270 Ohm one, because it would take more energy away from the circuit and cause the light to dim). The circuit worked, so I then started building the lantern, using a water bottle I found in the trash, a plastic cup, and the shiny wrapper of a sleeve of cookies, which acts as a reflective surface for the LED to rest inside.

The most difficult part by far was designing a switch, because at first I had no idea what would be a reliable and quick way to close the circuit. My initial design concept was to have the wires suspended in the bottle, and a piece of cardboard covered in tin foil that could be pushed into the bottle and touch both of the wires. To turn the light off, the tin foil strip would be pulled slightly out of reach of the wires. I also considered having a tin foil covered wire-like element which would spin between the on and off positions. But while building the prototype, this was all much trickier than I had envisioned. So I made one of the wires longer, and taped a piece of electrical tape to it, with the ends of the tape forming a pull tab outside the bottle. When the tab is pulled, the circuit connects, and when it is pushed into the bottle, the circuit is open and the light is off.

One of the first conceptual sketches

detailed sketch of what I had envisioned for the model

The final prototype!

The light is on and it works!

and when the switch is in the off position

Calculations:
battery = 8.99~9 V
LED = 3.2 V
current = 20mA

V=IR
(9-3.2 V) = 20mA (R)
5.8 V = .02A (R)
290 Ohms = R

Reading response: Poor People's Energy Outlook 2010, ch. 1 & 2

Having no previous experience or knowledge, this reading from Poor People's Energy Outlook 2010 really made me think about different issues concerning energy use and creation in the developing world. Most of the reading surprised me, but the one fact I could not forget was that 22% of the world's population does not have electricity (p. 2). It made me think about how we take electricity for granted, as well as other resources that come with that, such as the internet and lighting. I thought the readings were enlightening (forgive the pun), and took into account all the pros and cons of energy use. I had never thought about how burning wood for heat or lighting could impact health of people, especially children, or how most of their energy is spent gathering resources which could harm them and their families.

While reading, I was reminded of a lantern, which converts the energy of movement into light energy, as demonstrated in this music video (skip to 4:08, when the ball is actually a lantern).

Introduction

Hi everyone! I'm Kalyani, a senior majoring in Architecture and (probably) minoring in Art History. I'm really interested in engineering, especially the design aspects, and how it relates to architecture. I've taken a fair number of Art History and Studio Arts classes (including 3-D design this semester), and am looking forward to learning about the engineering perspective. I hope that this course will help me to think more critically about my own designs, as well as improve my skills in developing project ideas and thinking in new ways.