New freshman design seminar

This week I filed paperwork for yet another new course for bioengineering majors: a freshman design seminar.  The course idea was started by the Biomedical Engineering Society (BMES), a student club at UCSC.  They were seeing a lack of engineering in the first couple of years of the bioengineering major.  The first two years at UCSC usually have 12 technical courses and 6 general-education courses, but the bioengineering major has 16 required lower-division courses, mostly science and math.  That means that most students don’t get any engineering design courses in their first two years.

The BMES officers brought the idea of a lower-division project first to the dean of the School of Engineering, who encouraged them to get it created as a permanent course in the department.  They then brought the idea to David Bernick and me, and we brainstormed how to convert the project idea into a workable course that has no prerequisites.  We decided to go with a 2-unit course (about 60 hours total work) rather than a standard 5-unit course (about 150 hours) or a 7-unit lecture plus lab (about 210 hours), because bioengineering students can’t really afford to delay any of their technical coursework, so the design seminar has to be handled as overload.

We decided on winter quarter to offer the seminar.  Fall quarter was rejected, since students will need to be advised to take it and summer advising sessions do not really provide much opportunity for peer advising by fellow engineering students. Spring quarter was rejected, because I’ll have the circuits course (with 12 hours a week in lab, plus 3.5 hours a week in lecture, plus grading), so won’t have the time to do the freshman seminar as well.  David could probably do it in Spring, but it would be best if there were more than one possible instructor available.  It’s not clear who would teach the course the first year—I would have to take it on as overload if I did it, and money would have to be found to hire David to do it, as the course wasn’t even thought of when the curriculum leave plan was written for the next fiscal year.

The class is limited to freshmen and sophomore bioengineering majors (or premajors), but upper-division bioengineers will be encouraged to volunteer as mentors (and some may be paid as group tutors).

Here is the catalog copy I submitted (limited to 40 words):

A first course in engineering design for bioengineers. In co-operation with the Biomedical Engineering Society (BMES).  Students choose a design project and work on it in competitive and cooperative teams. Covers team building, design, prototyping, and report writing.

And here is the more detailed “supplemental sheet” that has the actual course description:

Undergraduate Supplemental Sheet

Information to accompany Request for Course Approval


Sponsoring Agency: Biomolecular Engineering
Course #: 88A
Catalog Title: BMES freshman design seminar
Please answer all of the following questions using a separate sheet for your response.


1. Are you proposing a revision to an existing course? If so give the name, number, and GE designations (if applicable) currently held.
This is not a revision to any existing course.

2. In concrete, substantive terms explain how the course will proceed. List the major topics to be covered, preferably by week.
This course is a project course for freshmen, done in conjunction with the Biomedical Engineering Society (BMES), a student organization on campus.

1. The class will choose a project for the quarter, with advice from BMES and the instructor.  Lab and fabrication facilities will be toured.
2. Instructor and reference librarians will introduce students to finding detailed information in the library and on the web relevant to the course (finding data sheets for parts, finding tutorials on relevant theory, searching for survey articles and application notes, using EndNote or BibTeX to maintain a bibliography, …).  Students will choose topics relevant to the project to research.
3. Students will present the results of background research and brainstorm approaches to the design problem.  Students will be assigned the task of finding and reading data sheets for components they might need.  Students will write a clear set of design goals for the project.
4. Teams will be formed to prototype different approaches. Dynamics of team formation and functioning will be discussed.  Procedures will be determined for abandoning unpromising approaches, merging teams, and starting new ones.
5. Weeks 5–8 will involve prototyping projects, with instruction in prototyping technologies and tools (laser cutter, soldering, drill press, glass bending, … ) as needed.  Written drafts of design reports will be required every 2 weeks—these are cumulative reports, not just what has been done since last time.
6. Weeks 9 and 10 will involve testing and comparison of the different design approaches and a collaborative final design report from the entire class that includes an analysis of all the different designs—their strengths and their weaknesses.  The final design report will be given as a public oral presentation, as well as in a written report.

3. Systemwide Senate Regulation 760 specifies that 1 academic credit corresponds to 3 hours of work per week for the student in a 10-week quarter. Please briefly explain how the course will lead to sufficient work with reference to e.g., lectures, sections, amount of homework, field trips, etc. [Please note that if significant changes are proposed to the format of the course after its initial approval, you will need to submit new course approval paperwork to answer this question in light of the new course format.]
Students will spend 3.5 hours a week in lab/lecture and about 3–6 hours a week in reading, writing, and group design meetings, depending on level of commitment to the course, making this course 2–3 units of effort.

4. Include a complete reading list or its equivalent in other media.
The students will be reading primarily about the background and components for the particular project they are doing, which will most likely be different each year.  For example, if students do a project on building a device to continuously monitor optical density in a liquid culture, they will be reading about the theory of optical density measurements, how liquid cultures are grown, light sources (LEDs, laser diodes, and incandescent lights), photo detectors (photodiodes, phototransistors, and photoresistors), and whatever other knowledge they need to design and build their prototypes.  Most of this reading will be from the internet and books or journal articles from the library.
Discussions on team formation may be based on a book like Teamwork and Project Management, 3rd edition by Karl A. Smith and P.K. Imbrie, but a shorter, more readable presentation is probably needed.  Short articles like
http://www.mindtools.com/pages/article/newLDR_86.htm
(“Forming, Storming, Norming, and Performing”) or
http://www.clemson.edu/OTEI/documents/teamwork-handbook.pdf‎
(“Successful Strategies for Teams”) may be more appropriate.

5. State the basis on which evaluation of individual students’ achievements in this course will be made by the instructor (e.g., class participation, examinations, papers, projects).
Students will be evaluated primarily on design reports and participation in project design.

6. List other UCSC courses covering similar material, if known.
This course is similar to capstone design courses and senior theses, but on a much smaller scale.  It is intended to be a first introduction to engineering design for bioengineering majors.

7. List expected resource requirements including course support and specialized facilities or equipment for divisional review. (This information must also be reported to the scheduling office each quarter the course is offered.)
Students will need access to a lab where they can use both electronic equipment and standard molecular biology equipment.  Baskin 287 has all the molecular biology equipment, but lacks a multimeter, bench power supply, oscilloscope, function generator, and soldering station.  Several of the electronics labs have the electronics equipment, but lack water, sinks, and biomolecular lab equipment.  A Bunsen burner for shaping glass tubes would be useful for some projects.
Students may also need access to the laser cutter and other fabrication tools in Baskin Engineering 138.

8. If applicable, justify any pre-requisites or enrollment restrictions proposed for this course. For pre-requisites sponsored by other departments/programs, please provide evidence of consultation.
There are no prerequisites for the course, as it is intended as a freshman seminar.  Enrollment is limited to bioengineering majors and pre-majors who are freshman or sophomores, to keep the freshmen from being overwhelmed by upper-division students.  A small number of upper-division students are expected to participate as group tutors.

9. Proposals for new or revised Disciplinary Communication courses will be considered within the context of the approved DC plan for the relevant major(s). If applicable, please complete and submit the new proposal form (http://reg.ucsc.edu/forms/DC_statement_form.doc or http://reg.ucsc.edu/forms/DC_statement_form.pdf) or the revisions to approved plans form (http://reg.ucsc.edu/forms/DC_approval_revision.doc or http://reg.ucsc.edu/forms/DC_approval_revision.pdf).
This course is not expected to contribute to any major’s disciplinary communication requirement, though it will include feedback on writing design reports so that students are better prepared for writing in upper-division technical courses.

10. If you are requesting a GE designation for the proposed course, please justify your request making reference to the attached guidelines.
This course is a group design effort, in which students agree on an overall design project, split into teams to prototype different approaches to the design, and work cooperatively both within the teams and in the class as a whole.  The course matches the Practice: Collaborative Endeavor (PR-E code): “Students learn and practice strategies and techniques for working effectively in pairs or larger groups to produce a finished product. For example, students might learn specialized practical information such as how to use change-management software to monitor and manage changes initiated by multiple group members. Alternatively, they might learn basic information about leadership, teamwork, and group functioning, which they can incorporate into their own group process. What is common to all courses is that some instruction regarding the process of collaboration is provided, in addition to instruction specific to the academic discipline and the products being produced.”

11. If this is a new course and you requesting a new GE, do you think an old GE designation(s) is also appropriate? (CEP would like to maintain as many old GE offerings as is possible for the time being.)
As this is a 2-unit course, the old GE designations, which were reserved for 5-unit courses, are not applicable.

Yesterday (Friday), BMES met with me to discuss whether the course description met their goals and how to get sufficient enrollment in the course. (I’d had to file the paperwork in a hurry, hoping to catch the last Committee on Educational Policy meeting of the year—we may still have missed it, in which case the course won’t be approved until the fall.)  The students who read the course description seemed to think that the course was what they were looking for.  I’m a bit worried about whether it can be kept to the workload of a 2-unit course.

We also talked a bit about possible projects for the first offering.  Two have been discussed so far:

• A low-cost optical density meter for continuous monitoring of OD 600 (with an LED light source) or OD 650 (with a narrower-spectrum laser-diode light source) of cultures on a shaker table.
• A pulse oximeter for measuring blood oxygenation.

Both of these projects have minimal analog electronics (basically just an LED or two and a phototransistor, with associated resistors).  The challenging parts are the mechanical design for the density meter (how do the sensor and shaker flask interact?  submersible sensor? culture pumped through a tube? waterproofing? autoclavable?) and the programming for the pulse oximeter (I think that most of the usual analog electronics can and should be replaced by programming, but is the Arduino powerful enough?  do we need a Raspberry Pi instead?).

We’ll be encouraging the members of BMES to come up with other project ideas, so that there can be a different project every year.  Another possibility that was mentioned is to build a thermal cycler for PCR, like the OpenPCR project, but the design work there has already been done, and the parts are more expensive.

The two projects we’ve been thinking of so far use only a few dollars worth of parts and a re-usable $22 Arduino board, so I don’t see any problem in just having students buy the components themselves.  It would be good for them to learn how to find and order parts from companies like DigiKey (though they are an expensive source for 650nm laser diodes: $9 vs. 5 for $10 at other suppliers).

Unless we get some corporate sponsorship, we’ll have to run this design seminar on a shoestring, as the School of Engineering relies on student lab fees for consumable parts, and those fees have to be approved about a year in advance. Anyone know a company interested in making a small donation to support such a freshman design seminar?  (It is not worth my time to go looking for a sponsor, but I’d be glad to put anyone who wants to make a donation in touch with the University Development people working with the School of Engineering.)

 

 

Arduino data logger at Global Physics Department

My son presented the Arduino Data Logger he wrote for my circuits class to the Global Physics Department on 2013 May 15.  The sessions are recorded, and the recording is available on the web (though you have to run Blackboard Collaborate through Java Web Start to play the recording).

I thought he did a pretty good job of presenting the features of the data logger.

Now that school is beginning to wind down, he’s started looking at making modifications to the data logger code again, and has updated it at
https://bitbucket.org/abe_k/arduino-data-logger/

He’s down to only three classes now (US History, Physics, and Dinosaur Prom Improv), though he still has homework to catch up on in Dramatic Literature and his English class.  He’s still TAing for the Python class also.

On Thursday and Friday this week, he’ll be taking the AP Computer Science test and the AP Physics C: Electricity and Magnetism test.  He’s having to take both tests in the “make-up” time slot, because we couldn’t get any local high school to agree to proctor the tests for him during the regular testing time.  Eventually his consultant teacher convinced the AP coordinator to let her proctor the tests, but by then it was too late to register for anything but the makeup tests. We’re way behind schedule on the physics class, so he’s just going to read the rest of the physics book without working any problems before Friday’s exam—we’ll finish the book in a more leisurely fashion after the exam. He won’t be as prepared for the physics exam as I had hoped, but at least the CS exam looks pretty easy to him.

One thing I didn’t realize is that schools can charge homeschoolers whatever the market will bear for proctoring the tests:

• Depending on the reasons for late testing, schools may be charged an additional fee ($40 per exam), part or all of which the school may ask students to pay. Students eligible for the College Board fee reduction will not be charged the $40-per-exam late-testing fee, regardless of their reason for testing late.
• Schools administering exams to homeschooled students or students from other schools may negotiate a higher fee to recover the additional proctoring and administration costs.

[ http://professionals.collegeboard.com/testing/ap/about/fees ]

We’re paying $145 per exam (not just the $89 standard fee and the $40 late fee), but I’m glad he gets to take the exams at all this year.

Tomorrow he and I are doing another campus tour—this time at Stanford. He managed to get an appointment with a faculty member, but we noticed that the faculty member is scheduled to be teaching a class at the time of the appointment—I wonder what is going to happen with that. I’ll report on the visit later this week.

Fifth day of circuits class

I feel pretty good about today’s lecture, though things got a little rushed at the end.

Three-resistor voltage divider for the first question.

I started with a “do now” question, similar to the one from Monday. Actually, I started with 2 questions. The first just asked what the output voltage would be for a 3-resistor voltage divider. The second repeated the question from Monday, but with the additional constraint that the power supply was 5 volts:

You have sensor whose resistance varies from 1kΩ to 4kΩ with the property it measures and a 5v power supply.  Design a circuit whose output voltage varies from 1v (at 1kΩ) to 2v (at 4kΩ).

Several students realized that the first question was a hint for the second one and that the variable resistor had to be RB or RC, and could set up the equations and solve for RA and RC.  This is a better performance than on Monday’s “do now”, but only about 1/3 of the class got it completely, and several of them were not confident of their results, so we again took time to go over the whole solution. I think that everyone (or almost everyone) understood the design process and how to set up and solve the equations by the end of the presentation, which I drew out of the students as much as possible.  I also mentioned that we could have solved the problem with a different circuit (putting RC in parallel with RB instead of in series), but did not further elaborate on that point.

The do-now plus going over the solution took about 33 minutes, which is a little more time than I’d like to be spending on these questions.  It would be good to get the time down to 15 minutes, but I don’t see how to do that without losing half the class.  If the problems are easy enough that everyone gets them, then there is no point to taking up any class time with them, and if they are hard enough that 1/3 to 2/3 of the class don’t get them, then they need to be gone over in class.

After the do-now, we spent a little time discussing the “fit” command of gnuplot, since the students have to fit models to the data they collect tomorrow, and I’m not providing them a script this time (though they can modify the script that was provided in the first lab).

Finally, we got to the theoretical meat of the class—we discussed what sound was (ending up with variations in pressure for a fluid, though we discussed briefly transverse and shear waves in solids).  Then I introduced microphones as transducers, trying to get the students to remember their elementary mechanics, so that we could do pressure→force→displacement→1/capacitance→voltage for electret mics.  The hardest part was getting students to remember that a spring-mounted object had force proportional to displacement (a lot remembered the energy was somehow related to displacement squared and got stuck on that formula).  I suspect that the local physics department would not be seeing a high score on the Force Concept Inventory for students coming out of their physics classes, as a lot of them seem to have concentrated on cramming formulas rather than learning fundamental concepts.  Someone did remember Q=CV and someone else could reason from wanting voltage proportional to displacement to needing constant charge which let me introduce both conventional capacitance microphone (with a large resistor to voltage source) and electrets.  I also explained that the electret had an enormous resistance, so we couldn’t get any measurable current out of it, and we needed an FET transistor to convert the voltage to a current.

Because both the do-now and extracting vague memories of physics from the students took longer than I had planned, we were a bit rushed for the last part of the lesson, which was a simple model of I_ds vs V_ds for the FET output stage of the electret mic. I asked for advice on drawing the plots for resistors and for current sources, and got the appropriate straight lines.  I then drew a smooth transition between them and claimed that the simple FET models usually consisted of a linear region at low voltage (which my co-instructor refers to as the “triode” region, a usage I’ve seen in some other presentations) and a saturation region at high voltage, and that we usually try to stay out of the sublinear region in between.

I also said that the saturation region is not really constant, but has a slight upward slope, since they will be measuring the I-vs-V characteristic of the electret microphones tomorrow, and they will certainly be observing that.  The lab handout gives them 4 models to fit: linear, constant current, an empirical blend of the two, and a model that allows current increase in the saturation region.  Neither the 3rd nor the 4th model match the ones usually used in circuit simulators, but I had trouble fitting parameters to those models, even with voltage-modulated channel lengths, so I gave up and produced simple models with few parameters that can be fit pretty easily. We’ll be revisiting FETs again before the power-amp lab (where they’ll use pMOS and nMOS power FETs to make a class-D amplifier). Somewhere around then, I’ll have to give them some usable models for how saturation current varies with gate voltage, which I deliberately did not cover in this lecture.

I’m a bit worried about how big tomorrow’s lab is.  There are again 2 parts:

• the DC characterization of the mic using the Arduino to gather data (plus a few hand-collected points for higher voltages than we can subject the Arduino to)
• designing a pull-up resistor to bias the mic into its normal operating range (in the saturation region) and observing the microphone output on the oscilloscope.  I also asked students to hook up their loudspeakers to the signal generators, to provide known inputs to the mic, and some other little stuff, but I’ll probably be happy if everyone gets the first part done and manages to observe waveforms on the scope.

On Friday, most of the lecture will be standard EE stuff by my co-instructor (probably current sources, Thévenin equivalents, and Norton equivalents).  I may have a do-now question at the beginning of the class, if I can come up with one that I think is pedagogically useful.

Fourth day of circuits class

Today’s class went much better than last Friday’s.

I took the advice one of the students gave me last we and started with a “do now” question.  (She had actually suggested an “exit ticket”, but I don’t have the time management skills to leave a block of time at the end of class.)  The question I asked was a design task that was easy if you knew what you were doing, but subtly harder than the standard sort of text-book question, because it was a design question, not an analysis question:

You have sensor whose resistance varies from 1kΩ to 4kΩ with the property it measures.  Design a circuit whose output voltage varies from 1v (at 1kΩ) to 2v (at 4kΩ).

I gave the students 10 minutes to work on this at the beginning of class.  A good question to prompt discussion (according to the peer instruction blogs and websites) should be answerable by 30–80% of the students.  More than that and the question was too easy to be useful, and less than that and the question is too hard for peer discussion to be worthwhile.  It turned out that no one had gotten it after 10 minutes (too hard to use as a peer instruction question), so we used it as the basis for a class discussion.

Almost everyone realized that the desired circuit was a voltage source and a voltage divider (not too surprising, since that’s the only circuit they’ve used so far).  The majority also realized that the variable resistor had to be on the lower leg, between the output and ground, and a couple of the students could articulate why.  I suggested the common heuristic of trying extreme values (0 and ∞) for the variable resistor, to see whether the output voltage would go up or down as the resistance changed.

The students were then able to set up the simultaneous equations to solve for the input voltage and the fixed resistance.  The hole in everyone’s thinking when working on the problem initially is that they had not considered the voltage of the source as a design parameter to solve for, though one student had asked about it. This was the blind spot I was expecting, so I was able to use it as a teachable moment.  After we had the equations set up using mainly student input, I gave the students another minute or two to solve them, and about half the class was able to solve them correctly in the time provided. (I suspect that everyone could have if given enough time, but I didn’t want to take any more time in class—those who didn’t solve it in class could practice their algebra at home if they needed to.)  One student had made an algebra or arithmetic mistake, and gotten a source voltage smaller than one of the desired output voltages.  This was also a good mistake to get, since we could use it to talk about sanity checks on results.

I think that the 20 or so minutes of class was well spent, as we uncovered several important misconceptions, and raised awareness of all unspecified variables as potential design parameters, reasoning using extreme values, and the usefulness of sanity checks.

After that, we spent some time discussing different temperature sensors.  From the students, I got thermistor, infrared thermometer, mercury thermometer+camera, and enzyme + other sensor (pH, conductivity, color, …). I added RTD, silicon band-gap, and thermocouple to the mix.  We talked a little about the advantages and disadvantages of each. At the end, I also threw in bimetallic strips and tilt switches for one-bit digitization of temperature.  I wonder how many students will look at the thermostats in their apartments and try to figure out what sensor they include.

For the remainder of the class, we talked about gnuplot commands, particularly the “plot” command.

After class, several of us went over to the lab, where my son met us and helped the students install the DataLoger, python, pyserial, the Arduino environment, and gnuplot.  While he was doing that, I borrowed an Uno R3 Arduino board and made sure that all the computers in the labs had the drivers installed for it.  We had 2 installation failures: on one Windows laptop, my son was unable to get the serial ports to work and one Mac laptop couldn’t install gnuplot.

The problem with the gnuplot installation on that Mac was not solvable by the techniques in the comments for Installing gnuplot—a nightmare, because all the methods there assume that you can install the command-line tools “make” and “gcc”.  The Mac had 10.6.8 installed, but the student had never bothered to install the development tools and had lost the original CD-ROM with the Xcode tools on it.  The Apple Developer site does not provide the command-line tools for anything older than 10.7.3.  The only workaround we could find was to download the 4.1GByte complete Xcode suite for OS 10.6.8, which I was not willing to wait around for. (Other students with 10.6.8 had no trouble installing gnuplot, because they already had the command-line tools, though they’d never used them.)

I did not look at the problem on the Windows machine (the student had to leave for class before I became available), but I don’t know that I could have done anything—my son knows more about Windows than I do, so if he was stuck, I probably would have been also.

Next year I’m going to want to do an install session before the first lab.  (Or, if we go to 2 labs a week, as the first lab.)

On Wednesday, I’ll start with another “do now” question, though I’m not sure what it’ll be on, since I’ve not yet gotten to the material for this week’s lab: how a microphone works. I’ll do a tiny bit of gnuplot (just the “fit” command) and try to get through how a microphone works and an idealized i-vs-v plot for the FET output of the microphone.

Plumbing karma

A couple of days ago in Is coding for everyone?, I wrote

Atwood makes an analogy to everyone learning to do plumbing, as if that were a ridiculous idea.  Personally, I think that everyone should learn a little plumbing: enough to clear a toilet or sink trap, or replace a faucet washer, and to know when to call in a professional plumber.

So, naturally, yesterday the kitchen faucet started dripping for the first time in about 15 years.  I figured I knew how to change a faucet washer, and that it would just take a few minutes today. Ha!

The first problem was that the faucet had not been opened up in so long that the threads had seized, so it took two people to get it apart: one under the sink holding onto the valve body with channel-lock pliers, the other using a lot of leverage with an 8″ adjustable wrench.  Even that wasn’t enough, so I had to go down to the hardware store for some penetrating oil and let it soak in for a while.

The Grohe faucet cartridge from the kitchen faucet.

Eventually, the threads eased up and the the faucet came apart.  But there was no washer to replace.  Instead what I had was a Grohe washerless faucet cartridge.  The Grohe cartridges are pretty good (which is why I hadn’t had to do anything with the kitchen faucet in so long), but when they fail, there’s not much you can do but replace the cartridge.

I tried smearing everything with vaseline and replacing the cartridge, just in case the problem was with the rubber gaskets, but the drip continued as before.

Unfortunately, the local hardware store does not carry Grohe parts (too upscale for Ace Hardware), so I had to bicycle 3.7 miles across town to Bay Plumbing, the closest place I could find that stocked the part.  I was pleased that their prices were essentially the same as I would have paid online (cheaper than some of the online places), and I could get the part immediately, rather than waiting 3–5 business days for delivery.

I was not so pleased that Bay Plumbing had no bike parking, so I told them about the Santa Cruz County Regional Transportation Commission bike parking program.   Unfortunately, I found out when I got home that SCCRTC no longer has the Bike Secure parking program.  That’s a shame, because there are still a lot of businesses that need bike parking!

In other news, the Arduino Leonardo that I had ordered arrived today. I ordered the Leonardo to test whether the data logger code worked with the Leonardo’s different way of handling the serial interface and different pin mapping.  But I goofed—despite my admonitions to the students in the circuits class to make sure that they got the right USB cable to go with the Arduino board they bought, I had not checked to see if we had a micro-B USB cable in the house.  We had so many USB cables sitting around, that I was sure one of them was a micro-B.  It turns out that they were all either B or mini-B, not micro B, so we were unable to test the data logger code on the Leonardo until I got a new cable.  (Actually, we had one micro-B cable, but it was a power-only cable for recharging my son’s bicycle headlight.)

I ordered a couple of the cables online earlier in the day, but they won’t come until next week, so after buying the faucet cartridge at Bay Plumbing, I stopped in next door at Santa Cruz Electronics to pick up a cable. Unlike Bay Plumbing, their prices were about three times what the online price would have been, so the only reason to buy there was to get the cable immediately. I’ll report on the status of the data logger software later, when I get an update from my son on the code he’s been adding today and when we’ve had a chance to test the Leonardo.