For the first assignment in the freshman design seminar for W 2015, I had students look on the web for ideas for projects they might want to do. I had set up the theme as “thrift store science”: do-it-yourself lab equipment of quality suitable for middle school or high school labs (though not necessarily with the durability that school lab equipment usually needs).
Grading for this assignment is simple—it is basically a check whether or not the students have done the assignment, submitting at least one project with a URL. I set the deadline for the project as midnight on Friday night, and 16 of the 20 students submitted by the deadline. I’ll add late work if the students ever submit it, but those students may have less chance of their project ideas getting accepted by the class.
Their next assignment will be to read project ideas that sound interesting to them from at least two other students and amplify on them—more links, discussion of possible difficulties, discussion of possible solutions, other ways to achieve similar goals, … . That discussion will happen on a private e-mail list for the class, as blog comments are too public to require students to participate. If any of the readers of this blog want to comment (for the students’ benefit) on any of the projects here, feel free to!
I’ll only comment on the projects after the students have researched and discussed them some more, though I may make some general comments about the relative difficulty of mechanical, electronic, and programming design. My experience is that programming allows more complex solutions, but simple programs are easier to build and debug than electronics for the same task, and both programming and electronics are easier to build and debug than mechanical designs. Modern engineering tends to push design problems out of the mechanical realm into electronics as soon as possible, and out of electronics into programming. Of course, any project will need some mechanical design, if only a box to put the stuff in.
Here is what they came up with, in their own words (with spelling corrected, but I’ve not added any comments—the comments are all from the students themselves):
Temperature sensor http://www.vernier.com/experiments/epv/1/build_a_temperature_sensor/
LED Color Mixer
I had an idea to make a IR temperature gun. This seemed like it would be a fun project that wasn’t too hard. This is how they work:
This is a fairly advanced version of it. I am not sure we can do something this technical but it contains a lot of helpful information:
I think it’d be interesting to make a Phototrophic biofilm microbial fuel cell, it sounds complicated but it’s just a fancy way to make a fuel cell that uses the products of microbes metabolism to create electricity. The interesting part about this project is the use of photosynthetic organisms and metabolism to create electricity, it would combine many areas of science from chemistry, physics, to biology together which I think would cover almost everyone’s interests. These fuel cells are very efficient and are relatively simple to make from what I’ve read and the diagrams I’ve seen, let me know what you think.
Links for information about the science behind the cells:
Instructions on how to make one:
The Vernier UV-VIS Spectrophotometer is used to measure the the absorbance of chemical and/or biochemical substances.
This Pasco Spectrometer is made to expand and sharpen the details up close of the images students are observing.
This project involves constructing a “pulse sensor” that would monitor your pulse. The project relays the infrared light reflected by the pulse into electronic signals. This project would be be great if we decide to use the Arduino.
In this project, a temperature sensor will be made using an Arduino board. This project will provide good practice for both programming and analyzing circuits.
DIY blood pressure monitor with a hand-cranked box as the power source. This website has many other DIY projects, including projects non-science related.
This sucks away fumes that can be present at chemistry experiments, which could cause hazardous situations. This website has many other projects.
A centrifuge that is simple and easy to use. Saves lots of money compared to centrifuges sold to schools. This website is a science magazine website that has many DIY projects.
An LED light casts a shadow on your object on the image chip, which creates a microscopic image that can be displayed on your laptop.
Can measure time very accurately in physics experiments. Can measure acceleration with 2 photogate timers. The DIY version is at a much lower cost.
“General Science” Sensor
(Pasco): Multi-function unit for detecting scientific basics– relative light intensity, light per area/illuminance, temperature (basic thermistor), environmental noise, voltage. User manual
(Pasco): Measure a solution’s conductivity. Does this count as wet-lab work? Household solutions could be used. User manual
. Note: we may run into the “thin glass rod” problem described in class (as with the pH sensor).
(Pasco): Detects ethanol in gas (or from the vapor a liquid emits). Seems like there’s a heating element whose applied current needs to be carefully monitored.
Doable with considerable effort:
This is my favorite so far -> Function/waveform generator (Pasco): synthesizes various waveforms (sine, square, triangle, sawtooth, etc) by cycling/stepping through frequencies at a designated rate. Should have wave type, frequency, step time/size controls as well as an audio output jack. A simple way to generate a sine wave, for instance, might be to cycle through a predetermined array of tones at even steps at a certain rate. Of course, a more advance signal generator would require high accuracy and a wide frequency range, so sticking to simple variable functions would probably be better. There are some guides online to compare; the main difficulty would come from finding parts and learning to solder.
: Uses three adhesive electrodes to measure electrical heart signals (and thusly rate). / Hand Grip Heart Rate Sensor
(Pasco): Determines heart rate using two metal handles. With all of these sensors I’ve posted, an interesting way to boost the difficulty would be to integrate an LCD to write out data in near-realtime.
Holter Monitor (Vernier): Continuous ECG, records and stores heart data over long periods of time (for later interpretation).
Induction Loop Generator + Receivers:
Take an audio signal, convert it to electromagnetic waves, receive it on a second device, and convert it back into audio/electrical signal for headphones. (Holy big bucks, Batman!)
A cool non-lab-equipment project would be a dot-matrix clock using LEDs.
An ultrasonic “eye” would be cool/sonic locator. With enough practice, someone with visual impairment might be able to navigate a crowded space.
… a couple of website links for interesting projects for the BME 88A freshman design class. I was interested in using the concepts of sensors used in colorimeters or spectrometers in the biomedical field, so most of my links are based on biomedical engineering.
ECG and Pulse Oximeter
The solid state heater is the norm with modern PCR systems (at least all the ones I’ve ever dealt with), but this leads to the problem of the thermal feedback loop and the heating/cooling systems being tricky to construct, as we talked in class. I have a modified version of this that I am attempting to design in AutoCAD, and I hope I can have a basic schematic in a weeks time, but my general idea is as follows:
A Cylindrical water bath container, split radially into 5 compartments which are physically isolated from each other to minimize thermal dissipation through the walls. The 5 compartments hold dH2O held at the 5 normal temperature steps (for Taq polymerase at least).
Denaturation Step: 94-98 Celsius
Annealing Step: 50-65 Celsius
Elongation Step: 75-80 Celsius
Final Elongation Step: 70-74 Celsius
Hold: 4-15 Celsius
In the center of the cylinder is a vial container (which extends out from the center over the water baths) which rotates to move the vials from step to step. It is spun by a small electric motor below the water bath assembly and the system moves as follows
elevate-rotate X degrees-lower
The advantage of this very preliminary idea is that it removes the necessity of changing the temperatures, instead only requiring temperature maintenance in the water baths, I do not believe the remainder of the project will be a significant issue, however testing the PCR machine would be difficult as PCR reagents can get pricey, (also a agarose and a gel box would be necessary and of course the loading dye and gel stain).
Idea 2: http://www.instructables.com/id/A-simple-DIY-spectrophotometer/
This idea seems simpler, the hardest part seems to be the circuitry around the photodiode, which might be problematic but I don’t have enough experience with circuitry to fully gauge the difficulty in that part of design. I am spending time learning the fundamentals of various electronic circuit components outside of class so hopefully I will be able to send out a AutoCAD schematic alongside the PCR machine.
A idea I was kicking around was maybe an incubator in a spectrophotometer that gives live updates on cell population density in some culture in the cuvette, this is in case the spectrophotometer is too easy for a full design project.
I think a constructing a photogate timer would be a feasible project for class.
With this tutorial, the cost would be around $65 (not including the photo-interrupter), however this figure is based off purchasing materials from the “sparkfun.com” website. The LCD screen for the readout and the FTDI basic breakout makeup most of the costs. Buying parts from Digikey would probably cut the costs down much more.
Our finished product would look more like the prototype in the beginning of the tutorial, since we don’t have the vernier photogates lying around (at least not to my knowledge). We could improve the design on the prototype photogate by creating a box enclosure for the hardware, like they did for their finished product.
I attached a powerpoint (http://web.stcloudstate.edu/zliu/presentations/MAAPT/10302010.pptx) I found online of another quick tutorial on how to build a photogate. This one is pretty simple, one reason being they didn’t use an LCD screen. Like the previous tutorial, I think we can improve on the design.
I also attached a pdf (http://www.becker.edu/wp-content/uploads/2014/06/Photogate.pdf) of another project for the photogate. In this one, they constructed their own photo-interrupter, which is probably the best way to go as far as lowering the costs and adding flexibility to the design.
Instructions for a cheap pH meter. I know this may be a bit ambitious with our current electrical skills, but pretty cool nonetheless.
Sound Level Meter
No idea if this is doable, or too easy, but sounds pretty cool!
UVA sensor to detect UVA radiation
Hey! so I’m not sure if this works and if it would be within the necessary work needed, but I was thinking of maybe designing a motion sensor. Here is the URL for a possible make it yourself sensor:
I found this website, Instructables, that teaches people how to make different types of gadgets or devices. I looked over the instructions and process of designing a voltmeter and it seems to be a pretty manageable project given guidance.
These two websites go more in depth about the different parts needed and seems to be a more advanced and digital model of the voltmeter compared to the first one. There will be circuit boards and chips needed, which would give students more experience with electronics.
This website offers a cheap design, using a total of less than 4 dollars to build. He encompasses the use of a pedometer in his design, which I found very interesting.
Stir Station (Vernier):
This device is a combination of a magnetic stirrer and a ring stand and consists of a small platform attached to a stirring ring stand. The platform is lit by LEDs to allow for better visualization of the liquid being stirred. I think that this would be an achievable project.
Color Mixer (Vernier):
This device studies the mixing of RGB light by additive and subtractive mixing. The kit comes with intensity-controllable LEDs a lens, and a double sided screen. I believe that this kit can be easily replicated, and we could possibly incorporate use of a colorimeter in later experiments. For example, sending “mixed” light into a solution and measure attenuation of light.
A possible idea for a project is a basic temperature sensor similar to the one sold by pasco.
Vernier has a lab which vaguely explains one approach.
And here is a very low cost tutorial on how to create a temperature sensor.
describes how to build a photo gate timer using an Arduino board which I thought would be useful since the Arduino board was what we had decided on for our micro controller.
also another design for a spectrophotometer, looks fairly simple, also seems to work well with the couvettes we were given.