Microblogging - crunch mode is on!

30 Apr 2011

Hey folks! Just a quick peep from yours truly here to give y'all a quick insight into the hectic last-minute tinkering of the BioBoard team. We're now 2 days, 23 hours and 38 minutes from the GGHC 2011 dead-line - that'll be Tuesday 3rd May at 00:00 hours - and officially in crunch mode. The project has shaped up really nicely in the last week - the two thermal sensors are finished, have been successfully wired up to Arduino boards, as has the NIR probe, and we've had live data transmission and graphing from the home-built digital thermometer. Rolf has also succeeded in bulding a pH amplifier circuit that let's us use a regular aquarium pH probe with our Arduino board. Otute unfortunately couldn't make the last meeting, so we've yet to see whether his home-built electrodes will work with the amp circuit. As for the dissolved oxygen sensor, we've come up pretty square against the same consistent problem every time, namely getting the dissolved ruthenium ion to form an even film across the mylar sheet. Surface tension keeps pulling all the solvent to the edges of the little glue enclosures (see the picture below), and Sean has been forced to go out of town on work, so it looks like we're going to have to accept that we won't make this happen before the dead-line. We're close enough to be fairly pleased with the collective effort nonetheless - I've taken a look at our original goals as stated in our project overview wiki:

As a minimum, we want to be able to monitor temperature, pH and dissolved oxygen. We'd also like to be able to measure biomass, either directly or by proxy. The current plan is to build a thermometer, a dissolved oxygen sensor and a biomass probe ourselves, and supplementing with a commercial pH meter. Failing that, we'll buy a thermometer and an oxygen probe as well and attempt to hack them instead, and concentrate on standardising data protocols, building the supporting controller hardware and making the graphics look pretty.

A quick comparison to current status: we are able to monitor temperature, pH and biomass by proxy. We've built two thermometers and a near-infrared (NIR) probe ourselves, and built a circuit for interfacing a commercial pH probe. We've not managed to build the dissolved oxygen sensor, but strongly anticipate to do so before Maker Faire. We've got standardised data protocols, supporting microcontroller software, a running database server and real-time data visualization. Pretty much what we set out to do. On top of that, it's been a great experience, everyone's made new friends in the process, we have a cool new device for our DIY bio projects, and a new global network of hackerspaces that weren't talking much before. All in all a straight win, no matter who takes the final prize home!

We're meeting again both Sunday and Monday, and will focus on getting all probes wired up to the same Arduino board and the data displaying on a single graph, making some cool video footage of the final build and getting our documentation squared away - the temperature and NIR probe wikis are coming along very nicely, but there's still lots of work to be done. We'll make sure to post everything in the final project blog post on Tuesday, but until then, here are some quick pictures from Wednesday's meeting:

The NIR probe wired up to a BoArduino

The NIR probe calibration setup - the glass beaker on the left contains green tea kombucha, while the cups contain a dilution series of Hibiscus extract.

Data from the NIR probe - the difference in optical loss between the kombucha and the darkest Hibiscus tea is 56% - pretty neat!

The oxygen probe, painted black inside to minimize internal reflection of the flourescing ruthenium complex - the uneven distribution of the film is clearly visible.

Real-time graph of data from our home-built digital thermometer!

That's all for now - we'll be back soon with the final installment of our BioBoard blog. Until then: be excellent to each other, dudes!