Darkening the shaker is highly recommended. The MPS has ambient light compensation but especially during fluorescence measurement, the signal is recorded over a period of several seconds, which is why external light can influence the measurement. For biomass measurement, the recording time is significantly shorter, but darkening can lead to better sensitivity (in particular in the lower OD ranges).

The biomass data is depicted in arbitrary units (a.u.) as backscatter signal. This provides a growth curve that contains all the information you would typically obtain from an OD₆₀₀ growth curve – but with much higher data density. However, if you specifically need your data expressed as OD₆₀₀ values, it is possible to take manual measurements at the beginning and end of the cultivation and use them to establish a correlation curve. This can only be done in post-processing, and the results will generally be less precise than a curve generated from a large number of offline OD₆₀₀ measurements.

As with any optical method, particles, color changes, or increased turbidity can affect the measurement. Anything that scatters or absorbs light may influence the backscatter signal. The extent of this effect depends on the concentration of particles and the degree of cloudiness. In many cases, if particle levels remain stable and the medium is not too turbid so that light can still pass through, reliable biomass measurements are still possible. Each situation should be evaluated individually. If you have doubts if your medium will work, please contact our support team.

No. The sensor relies on a stable shaken environment and cannot be used for a static culture.

The MPS can reliably measure biomass from an OD₆₀₀ of 0.5 and a cell culture concentration of 1 Mio cells/mL. Depending on the process these values might deviate slightly. Below this concentration the graph will stay linear even if cells started to multiply.

No. The sensor is not water-proof and should always be kept in a dry environment. Splashing water from a culture, e.g., from higher shaking speeds, especially when using high filling volumes and/or baffles, should be avoided under any circumstances.

The liquid moves in a circle when shaken. This movement is divided into so-called bins and a measurement is taken in each of these 32 bins. Depending on the bioprocess conditions, the bin should be selected in which the liquid has the best position above the biomass measurement window. Our default bin is 17. If you would like to optimize the binning settings, please contact our support team. The team will be happy to help you choose the right bin.

Our default wavelength is 940 nm, which is usually well-suited for all common bioprocesses. By using an LED in the near-infrared range, other media components are excited as little as possible, resulting in minimal interference with the actual backscatter measurement. However, for some bioprocesses, a different wavelength may be useful. If you have any questions, please contact our support team.