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26 Jun 2006 - No more exams: back to work...

Now that my ANZCA fellowship exam is out of the way, baby Anika is here and we’ve moved house, life is settling into a more manageable routine - and it’s back to serious work on the project.

The main focus over the next 6-12 months will be on:

  • jPNS - redesign to simplify the circuit, address the safety/usability issues and move to a surface mount design.
  • jPulseOx - build the proof-of-concept prototype, finalise the design and move to a production run of surface mounted devices.

The big breakthrough has come in the form of Texas Instruments' MSP430 line of microcontrollers - a range of low-power, affordable and diverse chips. I attended a half-day seminar from TI last week (430 Day) - which while feeling amusingly out of place as a doctor amongst a sea of engineers, was a great opportunity to get some more information on these little beasties. More significantly, a useful chance to get some advice from those working in the industry regarding fabrication options.

The MSP430FG437 in particular looks ideal for the jPulseOx, including not only 12-bit DACs, but also 3 OPAMPS for use as an instrumental amplifier and an integrated LCD controller. The good people at TI even have an app-note demonstrating a single-chip design for a simple pulse oximeter using the FG437. I stumbled across it at 2am early one morning when I couldn’t sleep - truly serendipitous. FG437’s run at around US$6.50 in 1k quantities, so a US$30 pulse oximeter is readily achievable.

The FG437 would also be suitable for use in the ECG module, and even more advanced monitoring requiring DA conversion and OPAMPS - so may form the basis for much evolution of the project components.

For the simpler devices, such as the jPNS, the MSP4302001 and up will be ideal. A single-chip design utilisting the MCU as a switch-mode controller may be possible, doing away with much of the circuit overhead present in the v1 jPNS design. Best of all, the F200x range start at US$0.55! Using these and moving to surface mount may halve the production cost for the PNS making an “every hospital in the South Pacific” goal readily achievable, and embarassingly affordable.

How many lives could be saved by ready access to a $30 pulse oximeter? Perhaps within the next year we will begin to find out.

8 May 2006 - jfish PNS in Bangladesh!

The jfish PNS v1 has just returned from being used by a work party in Bangladesh. This orginal design, while having some limitations that need to be addressed, has now been used in three countries where it has added significantly to the anaesthesia provided.

More photos, and even a short video, to follow. The PNS is set to return to Mongolia in the next few months...

6 Jan 2006 - Safety concerns and growing interest

Wow, in the quietness of the new year, the existence of the project has been picked up by an off-topic list at (thanks guys!). The safety concerns highlighted by Michael Neary are significant and worth highlighting. I’m talking to Michael and trying to nut-out some improvements to the design to neutralise these flaws.

In other (okay, pretty shameless) news, the jfish project is now the number 1 search result on Google when searching for ‘jfish’ (hah, take that jelly fish lovers!). Okay, okay, small victories...

Currently I’m focusing pretty heavily on exam study for my FANZCA (March & May) and preparing for our baby’s arrival. Hopefully I can keep things still progressing slowly through this period, before getting back fully into the swing of things post-exam in May.

Thanks for everyone’s interest and support for the project - let’s revolutionise world anaesthesia monitoring!

27 Nov 2005 - jPNS Package up for download

Ahh, I hadn’t realised, but the links to the jfish PNS package weren’t working. The ‘package’, a zip-file containing the gerber files, PCB artwork, schematics, build of materials and pdf’s of the relevant site pages, is now up and able to be downloaded. Aside from ever-increasing final-exam study, the two areas within the project that I’m focusing on are:

  • Looking into rewriting the jPNS firmware for the PIC12F629 without requiring Revolution Education’s PICAXE bootloader, and thus improving the access for others to the device. Alternatively, I may rewrite the firmware for a pin-compatible Atmel microprocessor.
  • Finalising the jfish Pulse Oximeter design specifications and then finding a suitably skilled biomedical engineer to produce a prototype device.

If anyone is interested in helping out with either, especially with a rewrite of the jPNS firmware in assembler (or higher level) for the PIC12F629, drop me a note.

20 Oct 2005 - jfish PNS in Myanmar!

The first overseas field deployment of a jfish device has been successful. Dr David Pescod (Consultant anaesthetist at The Northern Hospital, Melbourne, Australia) has just returned from Myanmar where he was working with Interplast Australia.

David used the jfish PNS to monitor the levels of neuromuscular blockade in his paralysed patients. He kindly captured both a photo and movie of the jPNS in action.

Thanks David!

27 Sep 2005 - Speaking at the ASA NSC

I have just left the Gold Coast after giving a talk on the purpose, goals and progress of the jfish project at this year’s ASA National Scientific Conference. It was a terrific trip, and very encouraging. The talk was well received and managed to nicely summarise the project in the available time, although the concept of ‘free’ medical equipment is still sufficiently foreign that it is a challenge to convey all aspects of the project.

The most interesting part of the day was a chance to observe the ASA’s Overseas Aid Subcommitte at work, by far the largest per-capita contributor to world anaesthesia. Excitingly, the OAS is very keen to contribute funding to help fast-track the design and development of the jfish pulse oximeter. I’m now focusing on finalising the design specifications for the jPulseOx and then tracking down suitably skilled biomedical engineers to produce the first prototypes. Exciting stuff!

22 Aug 2005 - Goes Live

The core documents have now been integrated into the site on the staging server and then transferred to the main jfish server. There are still quite a few documents to go up, the FAQs need to be filled out and the notes for final testing of the completed PNS need to be finished - but the core of the project is now up and ready to be added to!

8 Aug 2005 - Transfer of Site to DokuWiki

Not very exciting, but the staging site has been successfully ported to DokuWiki from Mambo, allowing the project documents to be properly collated and organised. Instead of hacking a wiki onto MamboOS, this allows the main site to be more easily maintained while also providing an incredibly collaborative environment.

The site will flesh-out rapidly over the coming weeks as documents are transferred into the wiki. Sub-sections of the documents area are editable by registered users. Jump in and share your thoughts and ideas!

5 Aug 2005 - First Production Nerve Stimulator Ready

A few hours with the Dremel and a perspex project box, and our first ‘production’ PNS is finished. The design will need further fine-tuning as it was reasonably labour-intensive preparing the case. The result is nevertheless very impressive looking.

I will have to do a final run-down of the production costs now that the first is finished.

28 Jul 2005 - Succesful Test of Production-Run PCBs

Successfully built the first production-run PNS circuit. Other than a slight programming error (DBS switch results in PTC because of a voltage-divider error due to slightly different resistor value), the stimulator works perfectly first time. Very nice. Next step is to package it for ‘real world’ use.

21 Jun 2005 - Received the First Run of PNS PCBs

A first production run of 15 nerve stimulator printed circuit boards has arrived. My only regret is the narrowness of some of the tracks, which I will need to have a bit of a play with Eagle to avoid next time. Regardless, they look very impressive.

The first test will be checking the PCB artwork with the circuit schematics, then placing the components and confirming that the design actuall works. The proof will be in this final step...

26 May 2005 - Finalised PNS Schematic

The circuit is finally working nicely, with not only a fully-functional breadboard mock-up, but a prototype on veroboard. After taking a bit of time learning to use Eagle properly (truly excellent stuff / works nicely on Mac OS X under X11) I transferred the final schematic over from an earlier program I was using (DesignWorks). The power of Eagle did take a little time to work out, but it eventually produced some very nice PCB designs which have been emailed to Futurlec in Thailand for production. is powered by the excellent Dokuwiki. Hosting, server, OS and design credits.
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