Working on using an SBC2 on battery power to log a number of physiologic variables which would be EKG, respiration, body movement (with spatial 3/3/3), body temperature and external sound level, light intensity and temperature. Also plan on using Phidgets GPS for plotting location and as a precise time source (when GPS signal available). Have already built the EKG amplifier but just need to redesign it for minimum power consumption. All data would be stored to a flash drive in one of the USB slots.
This unit is to replace heart rate and movement sensors from the now defunct company HeartLink which are essentially a Polar watch HR sensor with movement detection. SBC2 is not the most compact device to use and might have a hard time to convince patients to wear the hardware for 24 hours, but it's by far the simplest development environment I've come across (an earlier attempt to use the Stellaris evaluation kit crashed and burned as it was too much to attempt using low level programming given the amount of time I can devote to programming). Have ambulatory wireless accelerometers based on Freescale Zigbee development boards but they use an 8 bit processor and are only usable in my house.
Main problem I can see now is power consumption as the SBC2 draws 100 ma from a 6 V supply when communicating with it via putty and web interface and will likely need 200-300 ma with all sensors being sampled.
All programming is being done in C for the SBC2 portion and VB6 for the offline data analysis. The only sensor that Phidgets doesn't have appears to be a stretch sensor which is needed to monitor respiration (use a flexible band snuggly attached around the chest at end expiration). The 1 lb FSR incorporated into an elastic strap produced only a very low respiration related signal and was very chest-position dependent.
Just putting this project out there to find out if:
(a) anyone else has done anything like this as I don't like reinventing the wheel
(b) finding out what experience people have had using SBC2 in battery powered applications.
The final version of the project will be all open source.