Smartphone-Assisted Three Dimensional-Printed Acute Toxicity Detection: Mitigating the Impact of Sample Color

Accurate and rapid detection of toxicity in water bodies is critical for environmental monitoring, especially during environmental emergencies. Currently, smartphone-based sensors capable of detecting toxicity in colored water samples. This paper introduces the smartphone-assisted three-dimensional (3D)-printed acute toxicity detector (sATD), a novel device designed to quickly measure the inhibition rate on luminescent bacteria, thereby providing an efficient and affordable means for on-site acute toxicity assessment. To ensure stable image acquisition, the entire device is enclosed in a 3D-printed, sealed black box. Three different brands of smartphones were examined for the best performance. The sATD-IR (smartphone-assisted 3D-printed acute toxicity detector - inhibition rate) offers a straightforward and precise method for on-site luminescence inhibition detection, facilitating monitoring of acute toxicity in regional water. The sATD-IR system was validated by using a variety of samples. For example, the half-maximal inhibitory concentration (IC50) value for the heavy metal Zn2+ using the sATD-IR system was 1.727 mg/L, which is very close to the IC50 value of 1.656 mg/L obtained using the standard method. More importantly, our investigation examined how color can affect sample toxicity detection. A correction algorithm based on RGB analysis to accurately determine the inhibition rate for colored samples was proposed and validated.