Hi Wojciech,

To keep the cost of the device low, the MultispeQ has only one, rather broadd, ECS wavelength probe beam, and as we state in the paper on the beta device (Kuhlgert et al. 2015) link to open access paper: http://rsos.royalsocietypublishing.org/content/3/10/160592

"ECS can be measured using MultispeQ according to the methods described in Sacksteder & Kramer [45], using a green LED and a BG-18 filter covering the visible light detector on the add-on board (figure 6a). Currently, the measuring beam is provided by an unfiltered green LED, which provides broadband emission peaking at 525 nm. For rapidly decaying ECS signals, in the tens of milliseconds, the single LED measurement was found to be similar to that obtained with narrowband measuring light [45]. However, care must be taken when interpreting the broadband signal in traces taken over longer time scales (i.e. more than about 50 ms), and future versions of the instrument will allow for filtering the LED lights with interference filters."

For more information, refer to our original papers on this, e.g. Cruz et al., 2001, Avenson et al. 2004, 2005, which show that you need at least three wavelengths to fully deconvolute the electrochromic shift (ECS) signal from background over longer times (>~100 ms) required to separate the delta.psi and delta.pH components of pmf.

In principle, it should be possible to implement three appropriately narrow wavelengths int he device, as long as we could get the appropriate interference filters in the correct size etc. I've done some investigation of this, and its possible, but the setup costs would be high, so there would have to be some demand in the field to do this.

Dave

Dear Professor, Thank you very much for information. Wojciech