The DETECT Reader is a device called a luminometer. A luminometer measures the amount of light that is generated in the microtube that is placed over the shutter inside the device. The measurements are reported back as a Relative Light Unit (RLU) value. The higher the RLU value, the more light that is being generated by the sample.
With the DETECT/L assay, Sample6 built in a background light reading with our negative control which is used to define the threshold. An RLU signal above that threshold triggers a "presumed positive" when read with the iPad CONTROL app.