Printable fluorescent chip detects pathogens

October 26, 2017 //By Julien Happich
Fraunhofer IOF researchers have designed a printable fluorescence sensor including a multi-layered light emitter and photodetector combined with fluorescent dye laid out in micro-fluidic channels.

These fluorescent chips are being developed by researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena together with other industrial partners. The industrial partners provide the micro-fluidic chips (designed with tiny channels) which are then modified by the Fraunhofer scientists to include the light emitter and detector.

“We imprint a lamp as well as a photodetector – using a conventional, only lightly modified inkjet printer,” explains Falk Kemper, a researcher at Fraunhofer IOF. Four different special inks make it possible to imprint the lamp and detector on the chip. “Both the lamp and the detector have essentially four layers: an electrode at the bottom, an active polymer layer, another electrode and then a fourth filter layer,” explains Kemper. When the lamp’s electrodes are exposed to an electric current, the polymer layer glows and emits light. One filter sits on top of the lamp and allows only blue light through. Meanwhile, the dye glows yellow which is the only colour allowed to filter through to the detector.

In operation, one adds a drop of blood to be tested for pathogens onto the chip, the tiny channels on its surface guide the blood sample so that it mixes with special anchor molecules as well as with a fluorescent dye. When testing for a pathogen, the anchor molecule will bind only to the specific pathogen markers; all other molecules being allowed to pass on. The fluorescent dye attaches itself right at the top of the “stack” of anchor molecules and pathogen markers and will only attach itself to the specific pathogen markers.

The built-in lamp causes the fluorescent dye to glow which can then be detected by the photodetector if the pathogen marker is present. In the absence of pathogen, the fluorescent dye does not bind to the molecules and is simply filtered through.

“By printing the chips using an inkjet printer, we are progressing towards a cost-effective way of