Real-time detection of food-borne bacterial adenosine triphosphate (ATP) using dielectrophoretic force and a bioluminescence sensor

Real-time detection and quantification of food-borne bacteria draws increasing interest for evaluation of food quality and safety. Since living cells invariably contain adenosine triphosphate (ATP), the detection of bacterial ATP presents a fascinating method to determine its presence in food. Care must be taken however, to remove food-derived extracellular ATP, which will interfere with detection by ATP-luminescence. We developed a microfluidic and dielectrophoretic (DEP) device for intracellular ATP detection, which captures microorganisms by DEP force and washes extracellular ATP away. The yield of capture by DEP force at a 10 μL{bullet operator}min^-1 flow rate used in experiments was 87.7%. At constant ATP level the electrical sensor responded in proportion to the bacterial concentration. With a constant bacterial concentration and varying ATP, the signal did not change. These results show that the device can remove the extracellular ATP contribution from food to be sampled.