Sensor detects water contamination in real time

13th October 2015

SBT AQUA

Jordan Mulcare

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As things stand, a suspected contamination of drinking water requires that a technician first be sent out to take samples from the water supply. The samples are then cultured and analysed in the laboratory. Only after several days does it become clear whether the water is contaminated and which bacterium is the offender. Now, however, three former DTU students have developed a bio sensor that can measure bacteria levels in the water supply in real time, 24/7, 365 days a year.

This means that in the event of contamination, the waterworks can be notified immediately and take precautionary measures. The three DTU founders hail from the fields of nanotechnology, physics and computing, respectively.

The working principle behind impedance flow cytometry is simple. A liquid sample is continuously injected into a microfluidic channel with integrated electrodes over which a multi-frequency voltage signal is applied. Bacteria and particles transition across the electrodes which results in a change in impedance. The impedance change for bacteria is uniquely different compared to other non-organic particles and it is therefore possible to provide a very accurate estimate of both the bacteria and particle count in the sample in real-time. The working principle detects all bacteria species in the liquid sample, as every bacteria will result in a corresponding impedance change when they enter the system.

Today, all commercialised technology to detect bacteria requires either staining, incubation or manual sample handling. SBT Aqua will offer a product, which can perform online and real-time measurements of the bacteria level in aqueous solutions with no pretreatment of the sample, no incubation time and no manual sample handling. This is accomplished by using impedance flow cytometry. The technology is based on an electrical detection principle, where impedance measurements are used to detect particles and bacteria on a single cell basis. One of the key advantages of SBT Aqua’s product is that it will enable the introduction of sensor networks, where the sensors will collectively monitor multiple sample points in real time throughout the entire water distribution networkinstead of sporadically monitoring single sample points, which is the norm today.