It's been a long time and we owe everyone an update.
I know it’s been a while since our last update, but fear not, your generous support is not forgotten and the project continues. A few updates:
1. New Team Member: I’m pleased to introduce you to Russell Neches. Russell is a graduate student in microbial ecology at UC Davis, physicist-turned-microbiologist, and hardware hacker extraordinaire. He has joined the OpenCTD team to help us develop the next iteration of the instrument. You can find out more about his interests and experience in this Nature interview: http://www.nature.com/naturejobs/science/articles/10.1038/nj7469-131a
2. Status of the Mark II Prototype: Our initial goal for the OpenCTD was to design something that could be built cheaply using primarily off-the-shelf components. We wanted to minimize the use of specialized or custom made parts and focus on something that was truly do-it-yourself. We wanted interested and enthusiastic makers to be able to take our instructions and build a functional CTD primarily with parts from Radio Shack and their local hardware store.
After nearly 6 months of prototyping, it is clear that that vision was naive. The initial proof-of-concept never reached the level of precision or accuracy necessary to be used in the field and subsequent development revealed that the technical aspects of reaching those levels would put construction well beyond the reach of our targeted user base and raise the cost significantly above our $200 target.
Fortunately, my move to San Francisco has placed me among some of the most innovative instrumentation developers in the country. Which leads us to the next piece of news:
3. Developing an integrated platform: We are now in the process of developing a PCB (printed circuit board) that will encompass all the functionality of the CTD. The conductivity probe (which, in the final model will use gold electrodes) will be integrated into the board, so that it will be consistent and uniform across all units. For temperature and depth, we have a 30-bar board mounted sensor that incorporates both measurements into one tiny package - http://www.meas-spec.com/product/t_product.aspx?id=8685
and are exploring options for additional sensors. We’re in the process of designing and printing the circuit board and should have an initial update soon.
I know this may be disappointing to those who wanted to build your own, but after exhausting all possible angles, this is clearly the best option. Extreme DIY-ers can still develop their own PCB’s or prototyping board. The good news is that this may significantly reduce the cost (our first pressure sensor was $80, the new one comes in at $40, and printing circuit boards in bulk is inexpensive).
All designs, including that of the PCB will be open-source. There will still be quite a bit of DIY assembling on the user end, including housing and waterproofing the device, but as of now, I am not sure exactly how this will impact the donor reward of a copy of the instruction manual, as the manual itself is now secondary to the circuit board. Depending on cost, I’m considering sending a PCB to donors who would have received a copy of the instruction manual in addition to whatever documentation is needed to construct the CTD. Please let me know if you think that is fair.
All the best and we look forward to an exciting year for the OpenCTD project.
~Andrew, Kersey, and Russell