Lab on a chip promises advanced diagnostics

Gary Boasg, boas@eggship-media.com

Diagnostics often involves testing blood or other biological samples to see if they contain molecules indicating the presence of a particular disease or disorder. Typically, doctors send the samples to a laboratory and wait several days or more for the results.

Now, however, researchers with the European Union-funded NEMOSLAB (Nano-Engineered Monolithic Optoelectronic Transducers for Highly Sensitive and Label-Free Biosensing) project have reported a portable lab on a chip that can identify target molecules in samples. They note that, in some cases, patients even could perform the tests at home by using the technology.

The chip’s novelty lies in the monolithic integration of silicon LEDs optically coupled to photodetectors and biofunctionalized thin silicon nitride waveguides, said project coordinator Konstantinos Misiakos of the National Centre of Scientific Research (NCSR) in Athens, Greece.

“Planar waveguide sensors are not new,” he said. “However, the monolithic integration of silicon LEDs and photodetectors optically coupled to the waveguides is novel” and opens new avenues in the development of optical lab-on-a-chip technology.

The work, performed at the Institute of Microelectronics at NCSR, grew out of the recent development of monolithic silicon optocoupler technology. In collaboration with the Institute of Radioisotopes and Radiodiagnostic Products, Misiakos and colleagues demonstrated the use of such optocouplers as sensitive biosensors. The scalability of the technology – arrays of optocouplers can be assembled on the case chip using the same process – the on-chip instrumentation offering all the advantages of optical biosensing, and the availability of integrated microfluidic channels then motivated them to realize the lab-on-a-chip device using a CMOS-compatible process.

Researchers have described a lab-on-a-chip device with monolithic integration of silicon LEDs optically coupled to photodetectors and thin silicon nitride waveguides that can contribute to a range of applications requiring multianalyte biosensing. The device here is shown from the emitter side, with the emitters on the right and waveguides (purple strips) extending to the detector (not shown).

The device could contribute to a number of applications, “mostly point-of-care applications where multianalyte biosensing is crucial,” Misiakos said. For example, an infertility treatment center in Dortmund, Germany, plans to explore the potential of the device for measuring fertility hormones in women seeking to have a baby through in vitro fertilization – the device can test for up to nine different hormones at the same time. Currently, these tests must be performed in the clinic daily. With this device, women could perform the tests themselves at home.

The device also can test, at the same time, for multiple mutations in the BRCA1 gene associated with predisposition to breast and ovarian cancer. Thus, it might enable doctors to screen for a predisposition to hereditary diseases.