The second version involved a whole different enclosure and built in data logger. The conversion method and software was also quite different. We relied solely more on spectrometry for the sensory mechanism and utilized the wavelength extension module (Sonar conversion) and data logging. We didn't need any WIO Link or Particle Dev boards for v2, and sort of built our own sensitivity tip. Version 2 also relied on off the shelf software and its expansion even went a step further.