I challenged students to come up with possible design projects:

Turn in by e-mail by midnight Friday, 2014 Jan 10: Look on-line for projects that might be interesting to design or build this quarter. Look at sites like Pasco and Vernier for ideas about what schools with money have in their labs. Look for do-it-yourself lab equipment ideas on the web. Turn in an annotated list of URLs for interesting sites as plain text, cut-and-pasted into e-mail to karplus@soe.ucsc.edu. The annotation need not be extensive—a sentence about each web site, telling us what project(s) it has information about should suffice.

Here are the responses from students, lightly edited and reformatted to get a little consistency. I'll gradually add comments as I get a chance to look at some of the web pages. I'll try to make my comments stand out visually (perhaps italics and a color change?).

From Alejandra:
The projects that interested me the most were building a rover, a centrifuge, and a 3D printer from e-waste.
Cute, but way outside our price range and time.
Two students found this article. I've commented below on Chad's post, since he had a better link to the same project.
The article points to a list of 3D printers and printer kits. There are good reviews in Make: Ultimate Guide to 3D Printing, though that costs $10 plus shipping. (I have a copy at home.) I think that $200 for a kit is not really appropriate for this class, and designing our own 3D printer is too ambitious for a 2-unit course.
From Alexander:
Water Ripple tank
I found the idea for the ripple tank from Pasco's website. The ripple tank can be used to examine topics such as refraction, reflection and the Doppler effect. Other websites for a simpler design.
A ripple tank is a nice way to demonstrate wave propagation. The $800 Pasco one has a pair of vibrating point sources whose frequency and phase can be changed (though it isn't clear that arbitrary phase differences are supported). The use of foam on the edges of the tank to reduce reflections off the sides of the tank is a good idea. The mathinscience site shows how to do a single point source or two point sources in phase. Frequency is harder to adjust, as it depends on the resonant frequency of a a clamped plastic ruler—the ruler would have to be clamped at different distances to get different frequencies. The tank from Arbor Scientific is just a shallow clear plastic box with some opaque plastic parts to put in it ($50). The waves are generated by hand manipulating the parts (though the ruler method described in the mathinscience site could be used). They have a more expensive version ($250) that has a motor with an eccentric weight as the wave driver (a lower-cost method than the voice coils of the Pasco system).
Centripetal Force Projects: Force measuring apparatus http://www.vernier.com/products/lab-equipment/cfa
I took this project idea from Vernier's website. The design project here allows students measure centripetal force along with angular velocities. The design involves the use of weights, a study frame and sensors for calculations. Further details can be found on the website.
This is a huge collection of different devices, some of which would be easy for us to duplicate, some of which would be hard. For example, see the homemade "superpulley" that my son and I used for home school physics.
Centripetal Force Projects: Centrifuge
A rotational motor that we can incorporate into the design of a centrifuge: http://www.pasco.com/prodCatalog/ME/ME-8955_rotational-motor-drive
Pasco products are always very expensive. $215 for a motor on a stand with a low-resolution disk for a photogate is ludicrous. Consider sources like Pololu, BatterySpace, Solarbotics, Sparkfun, R/C Dude, or other robotics hobbyist sites.

This video showcases an excellent design for a high-powered centrifuge: http://www.youtube.com/watch?v=v3sF11vXLsU

I wouldn't consider any centrifuge that can be run at high speed with the rotor not fully enclosed in a safety shield an "excellent" design, and the power levels on this centrifuge are outside the price range for the class.

Weather Station
Weather has always been of interest to me, creating a weather station with sensors giving info about pressure, humidity, temp wind speed ect would be a great project. Here is a link back to Pasco's website about sensors and weather.
Sparkfun has a whole collection of weather sensors, though I think that Adafruit's price on the BMP180 barometric pressure sensor is much better. You might want to look at Sparkfun's biometric sensors as well to see if something else interests you.
An absolute pressure sensor with a digital interface costs under $10 (in single-unit quantities). We could fairly easily hook up such a unit to a microprocessor like an Arduino, except that they are surface-mount parts, which are hard to work with by hand. For $10 we can get a "breakout board" that has a higher-resolution barometer and temperature sensor.
Although there are a few little things on this site we could do, most of it looks like it is intended for deep-pocket hobbyists.
From Alexandra:
This is a link to a pdf with different articles that show simplified versions of various lab equipment. One would have to look up each article in order to get instructions on how to make something.
The article is Journal of Chemical Education 61(4):385, April 1984 and is buried behind a paywall. It just lists other, older Journal of Chemical Education articles. Because UCSC has a subscription, the articles are available on campus. From off-campus, you have to learn how to use the off-campus access methods. Note that you must visit the library to activate the barcode that you can later use for off-campus access.
This link shows a spectrometer made out of a cardboard box.
Although you already shot down the idea of a DNA sequencer, this is still an interesting article.
I didn't mean to say that we couldn't do a sequencer—just that Nader Pourmand's bioinstrumentation class (BME 140/L) is planning to do that, so it might be better for us to do a different project here. However, this article is not about a sequencing machine but a PCR machine, which we discussed as a real possibility (though perhaps a bit pricey for the class).
DIY x ray machine $20 This is taken from the old Amateur Scientist columns from Scientific American (July 1956). I have a CD-ROM with the complete collection of Amateur Scientist columns, though I had trouble opening it on my laptop (it opens ok on my iMac, though the index isn't really usable, since it relies on a PowerPC program). The $20 price in 1956 would be about $172 today, and lab saftey requirements are much stricter. I don't think I'd want us to be building an unshielded X-ray source.
Youtube video of DIY Magnetic stirrer
There are lots of magnetic stirrer DIY projects, since the design is so simple. I generally prefer text+pictures to videos for conveying design information (like this Instructables version), because videos are a very slow way of conveying detailed information. They can be useful for showing things in motion, though.
From Brieanna:
I was thinking about making affordable incubators for high school & middle school classrooms. I think if we made affordable incubators, kids could buy them for their own science fair projects. I know it was incredibly difficult getting my bacteria to grow for my 8th grade science fair project. It would have been nice to have one easily at hand.
Here's the site for high school lab equipment.
Carolina Biological is indeed a popular store for high-school biology teachers. You might also want to look at Flinn Scientific, Arbor Scientific, and Nasco. (I was going to suggest Bio-Rad as well, but their website behaved so badly I'mnot even going to link to it.)
Here's a very cheap incubator design, made originally for chickens, I think can be modified.
I think this description got attached to the wrong URL. These are normal, expensive, lab-grade incubators.
Here's chicken design for an incubator on instructables.
This instructable looks pretty good, but it only provides a heat source, not a way to cool. The designer found that he had trouble with the incubator on hot days in Texas, as it got too warm. Thermal regulation with a 25W bulb and a water-heater thermostat is probably not very tight. A similarly simple design for a lab incubator (rather than an egg incubator) can be found at http://citsci.blogspot.com/2009/10/incubator.html. There is a slightly more complicated on Hackteria.
A how-to on how a lab incubator is made.
This site describes the manufacturing of commercial lab incubators, which gives some idea of what features are considered important, but does not lend itself to DIY construction.
From Chad:
http://phys.org/news/2013-11-diy-scientist-lab-equipment.html A Scientist's Guide to Making Your Own Lab Equipment
This web article advertises Joshua Pearce's book on creating cheap lab equipment by yourself. The article then goes on to state that with the ability to create lab equipment, scientists will have more autonomy and become (somewhat) less dependent on grants. For the record, I've been looking for this book in the UC Library System. There is a copy at UC Merced, but it is currently being used.
This book looks promising. Go to the Science Library and request it through InterLibrary Loan.
http://diybio.org/blog/ DIY Bio
An excellent blog featuring numerous project ideas about perform biological experiments without expensive equipment and a fully stocked laboratory.
DIY Bio looks promising. So does Hackteria
http://www.popsci.com/diy/article/2013-07/how-build-your-own-diy-centrifuge How to Build Your Own DIY Centrifuge
http://diybio.org/2009/12/30/diy-centrifuge-using-dremel-tool DIY Centrifuge with Dremel Tool
This article and video describes the Dermel Tool Centrifuge, which is made from a 3-D printed plastic piece attached to a drill head. This describes how to make a centrifuge and where to obtain some of the materials.
The Dremelfuge head makes good use of a Dremel motor (or other rotary tools with a similar chuck). I think that it needs to have a sensor added to measure the speed, as I don't believe that the Dremel tool is running at full speed when the Dremelfuge is loaded with tubes. The Dremelfuge head is available 3D printed for $48. A little more information can be found on the DIY BIO site.
http://www.ehow.com/how_4587586_molds-plastic-casting.html How to make plastic mold castings
A useful guide for making plaster molds for shaping resin. It could be very useful for a number of projects needing sturdy, plastic shapes.
Resin casting is supposedly a good way to make small runs of parts (10s to 100s), but I don't know that these instructions are a good set to work from. A lot depends on what sort of object you want to cast, whether you can do it with a one-part mold or need a multi-part mold, and what sort of resin you want to use. There are lots of sites about resin casting and what resins to use. I've never done it, but I looked into a little a while back.
From Corrie:
DIY Bio Inkjet Printer
The BioPrinter ended up costing about $150, using the InkShield kit and scavenging old CD/DVD drives to make the positioner. This project is cool, but requires a fairly high level of both mechanical construction skill and programming ability.
DIY Micro Dispensing and Bio Printing
There doesn't seem to be much information on this page that allows you to figure out what they did or how they did it. There are some pointers to potentially useful resources.
Hacked Optical Mouse
The idea here is to repurpose the optical-sensor chips of optical mice either to sense flow in microfluidics or to act as a very low resolution camera. I'm not sure what use cases there are in middle/high-school lab classes.
Wearable Bio Circuit
This looks like a fashion project, and not a very well done one. We could design and build a heart-rate monitor (either optical or EKG). The last lab in BME 101/L is an EKG circuit.
From Deekshita:
A simple accelerometer to measure G's or gravity pressure change, while on a roller coaster.
That post has very simple 1-axis and 2-axis mechanical accelerometers, suitable for middle-school demos. It might be more fun to hook up a 3-D accelerometer to a microprocessor and record acceleration as a function of time to dsiplay on a graph. Accelerometers are now very cheap chips.
How to make a digital microscope with basically the parts of a smaller, cheaper microscope.
Rather a neat slide positioning system for a microscope. One of the many uses for stepper motors from old CD-ROM drives.
Create your own magnetic field sensor.
Rather a lot of circuitry for a not very accurate magnetic field-strength measurement. For about $1, one can buy an off-the-shelf magnetometer chip which has 3-axis measurement up to 1 mTesla with 0.1μTesla resolution.
From Haley:

My idea: create synthetic pigs/frogs/cats/other living things that are raised and killed so that students can dissect them and learn about their anatomy.

As far as I can tell, no one has yet tried this. This may be because it is too difficult/expensive to try. However, I thought it would be a great solution to the ethical problem of raising life and then promptly killing it for none other than our own benefit.

The first link shows data about how, in some cases students learned and performed just as well using a virtual dissection program (online) as those who dissected the animals themselves. However, in some cases those who used the virtual dissection (examples I found of virtual dissections are from link 2) did not do as well as those who had actually dissected.

For this reason, I think it would be worth it and beneficial for all living beings if we were able to construct synthetic animals for the purpose of dissection. That way, students are not being neglected information and living beings are not being raised and killed for our own knowledge.

There are a lot of dissection models on the market already (see, for example, http://www.thefind.com/family/info-dissection-model). I'm not sure how we would go about creating better ones or cheaper ones. Ideas?
From Joanna:
This is a sound level sensor, which I think will be pretty cool an inexpensive to replicate by using some sort of sound wave strength sensor connected into a basic circuit.
Sound-level meters are a bit tricky, because of the need for matching the frequency response to human hearing. I've discussed an analog implementation of a cruder loudness sensor in a series of posts: http://gasstationwithoutpumps.wordpress.com/2013/07/11/logarithmic-amplifier/, http://gasstationwithoutpumps.wordpress.com/2013/07/12/logarithmic-amplifier-again/, http://gasstationwithoutpumps.wordpress.com/2013/07/16/precision-rectifier/, http://gasstationwithoutpumps.wordpress.com/2013/07/17/improved-rectifier/, and http://gasstationwithoutpumps.wordpress.com/2013/07/31/microphone-sensitivity-exercise/. I think that if I were to implement a loudness sensor now, I would use a faster processor than the Arduino boards (maybe the Freedom KL25Z boards), and do as little as possible in the analog circuitry and as much as possible with digital processing.
This is a magnetic stirrer with a hotplate for less than $30.
One could probably go even cheaper if using a simple resistance heater, rather than a Peltier device for the temperature. Some of the other magnetic stirrer instructions had better instructions for how to center the magnet.
This is a sample rotator used for mixing solutions that require constant and gentle motion.
I've not see an almost vertical rotator like this in any of the labs. More often, I see "shaker" trays that swirl liquid in a large number of flasks or vials.
This is a pipe that copies DNA by using the heat of a lightbulb!! Cool
I commented on this design under Stella's link to it.
This is not so much lab equipment, but I thought it was pretty cool. It's a finger sensor that can serve as a security tool.
Wiring a biometric sensor to a lock is not very difficult—we can probably do this if people to choose to. I wonder whether the box is locked or unlocked when the batteries fail. If locked, I wonder whether there is a power input to use if the batteries do fail.
This might be a bit more expensive, but it would be cool to make our own DC power supply.
That's a very old-fashioned power supply, with a huge, heavy transformer. Modern ones use a high-frequency oscillator on the "AC" side so that they can use a much smaller transformer. Also, the linear recitifiers used are very inefficient. Modern power supplies generally use switching regulators for efficiencies around 90%. If you need very clean power, then the switching regulator might be followed by a low-dropout linear regulator (abbreviated LDO).
It's a build your own spectrometer! Now that I now what it's used for I think it would be an awesome project.
This is just a spectroscope not a spectrometer (that is, it let's you look, but not measure). The idea can serve as a basis for a spectrometer, though. See also my comments on the link for a similar cardboard spectroscope from Alexandra's list.
From John:
http://www.vernier.com/products/sensors/col-bta/ and http://www.home.zonnet.nl/rsetteur/aquarium/karel/colorie/coloriemeter_eng.htm
We could find a way to make a colorimeter that measures the concentration of a solution
A colorimeter is totally doable. It is one of the projects I was thinking of: http://gasstationwithoutpumps.wordpress.com/2013/09/22/projects-for-freshman-design-seminar/
http://www.vernier.com/products/sensors/pamp/ or http://www.angelfire.com/planet/funwithtransistors/Amp-400_W.html
We could find a way to amplify power to demonstrate current, or make an amplifier for a speaker, which could be demonstrated.
Almost any sensor we do is likely to require an amplifier. We'll probably use a pre-designed amplifier for this class, but you'll learn to design them in BME 101/L.
From Lindsey:
This website explains how to make an electronic pH reader. It describes how to make the pH probe, the voltmeter, and the circuit.
I said in class that I didn't think that we had the capability to make our own pH probes. Lindsey correctly took that as a challenge, rather than final decision, and found this site on using a Christmas-tree ornament to make the glass bulb. Of course, one can buy a pH meter for $8 with 0.1pH precision and accuracy, so making your own probe is not going to make a much cheaper lab instrument. It is also possible to buy pH probes off the shelf, with a bewildering variety of options. See http://www.hannainst.com/usa/electrode_choosing.cfm for an explanation of some of the options. A refillable probe costs only $7.50 (plus shipping), if you want to make just the electronics part of pH meter.
This site shows how to make cheap titration lab ware.
There seem to be 2 ideas here: building a lab stand out out an erector set, and using a disposable serological pipette with a rubber bulb as a standin for a burette. Both are good home-lab solutions, but this doesn't seem to be leading to a design task for the class.
This page describes how to build a laser interferometer.
Using a CD case as a partially reflective mirror allows demonstrating laser interferometry with a couple of mirrors, a laser, and a light detector. This implementation used a toy (Spynet Laster Tripwire) to keep the price very low.
From Marissa:

General DIY lab equipment

The hometrainingtools site has many varieties of science equipment and experiments.


centrifuge—perhaps powered by a bike
A generic Wikipedia article on centrifuges does not give us much to go on for doing a design. The more specific DIY articles on centrifuges found by other students are more productive.
No links provided
The first microscope looks like it would be fairly cheap, assuming that you can salvage lenses from disposable cameras. The second one looks more expensive than just buying a microscope.
gel electrophoresis (Inexpensive Electrophoresis)
Building a gel box out of laser-cut acrylic should be straightforward. I don't think that their unspecified metal for their "conductive plates" is very informative. They are likely to get considerable metallic ion contamination of their samples if they don't choose wisely.

The site http://teach.genetics.utah.edu/content/build_gel_box.pdf gives detailed instructions for building a gel box (without needing a laser cutter). They use disposable wire electrodes, though they warn that "If you use copper wire, it will react with the electrophoresis buffer, turning the buffer blue." http://cheapassscience.wordpress.com/2011/10/05/electrophoresis-electrodes/ discusses one persons experiments with different electrodes. The gel box that this was for is described (with detailed instructions) at http://citizensciencequarterly.com/2011/10/cheapass-science-gel-box/ Interestingly, he did not try Ag/AgCl electrodes, which are not difficult to make and much cheaper than platinum. (We make and characterize some Ag/AgCl electrodes in BME 101/L). Even with platinum wire, the gel box is much cheaper than commercial ones. We would have to design the power supply for the gel electrophoresis also.

From Stella:
Infrared Pulse Sensor
I think that a light-based pulse sensor is within the scope of what we could design in this class. I've done several such designs, looking for a sweet spot that doesn't include too much electronics or too much programming. Look at Pulse detection with light Optical pulse monitor with little electronics, and Digital filters for pulse monitor. Right now, it looks like we either need a high-gain amplifier with analog filters or some digital filters in the microprocessor. I don't think the class has enough math to understand or do the digital filter design. Even the analog filters would be a challenge. We could take the electronics/programming as pretty much a black box, and just focus on the mechanical design of the attaching the sensor to the body.
Gene Machine:Copies DNA using heat of lightbulb
This is one of the cheapest PCR machines I've seen. An incandescent lightbulb for heating is a standard trick for homebrew equipment (see all the incubator designs, for example). This design does not do active cooling, but just blows ambient air in to cool down to room temperature. It relies on having a low thermal mass to get quick enough cooling and heating. One might improve on it by having dimmer circuitry for the bulb and motor speed control for the fan, to get finer control of the temperature—but the extra complexity might not get you much improvement. The OpenPCR project provides finer control using a Peltier device for thermal cycling, with a range of 10°C to 100°C with a ramp of about 1°C/sec and an accuracy of about ±0.5°C, but at cost of about $600.
"Smart Gauze": sensor in gauze and detector in the phone to locate non-metallic objects during surgeries.
The idea here was to use NFC (near-field communication) tags in surgical gauze to make it easier to keep track of all the gauze and make sure none gets left behind in an operation. NFC is one type of RFID (radio-frequency identification) that is specialized for short-range communication (see http://blog.atlasrfidstore.com/rfid-vs-nfc). NFC has some extra capabilities that don't seem very useful in this context, and the range limitation of NFC may make it difficult to find and detect gauze that is not right on the surface of the body—the larger range of the older RFID tags There is discussion about autoclavable glass-encapsulated RFID chips at http://www.sparkfun.com/products/9416
From Zhong:
A low cost homemade vacuum filter to filter heterogeneous solution fast.
Flipping the piston seal in a bike pump to make one that removes air rather than pushes air is something I did for a science fair project in 4th or 5th grade. You don't get very good vacuum that way, but enough for a vacuum filter, which is only looking for a pressure difference of 0.2–0.5 atmospheres anyway. (The flask they showed might shatter with a full atmosphere difference.) You can get somewhat lower pressure in a sturdier container with a hand-held vacuum pump for about $30. (I bought the Actron pump from Amazon for about $40.)
Lab equipment examples, built by students and adults.
This looks like a good list of projects, selected for quality by being winners of a contest for DIY lab equipment.
Maxbotix Sonar senor/diagrams+ direction
I have a Maxbotix ultrasonic rangefinder—also a Pinggg one. They are good for detecting large objects, but not so good for small ones. They are useful for high school physics. See my posts http://gasstationwithoutpumps.wordpress.com/2011/09/23/physics-lab-1-ultrasonic-rangefinders/, http://gasstationwithoutpumps.wordpress.com/2011/10/01/physics-lab-2/, and http://gasstationwithoutpumps.wordpress.com/2011/10/08/physics-class-progress/.
PIR Motion Sensor
A passive infrared motion sensor is certainly an easy thing to interface. What would you use this device for in a science class? Come up with a good 'use case' for it.

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