GaN chips offer bedside cancer diagnosis
Electronic detection of so-called biomarker molecules could accelerate disease diagnosis, and GaN transistors are one of the cheapest options available to achieve this.
That s what Fan Ren of the University of Florida reckons, and he's recently made his case by detecting a biomarker that signals acute renal failure down to 1 ng/ml. At this level, the researchers say that their device could be useful for preclinical and clinical applications.
In a November 26 Applied Physics Letters paper, Ren and his collaborators modified a GaN high-electron mobility transistor (HEMT) from Nitronex by attaching kidney injury molecule-1 (KIM-1) antibodies to it.
When KIM-1 is exposed to the transistor it then remains attached to the antibodies, affecting electron mobility and hence the current passing through the HEMT.
KIM-1 is a molecule found in the urine of people suffering from acute renal failure. Technology exists to detect its presence, but is either limited to only testing for one disease, or is too slow for rapid bedside diagnosis.
“We can functionalize devices with different antibodies using a commercially available inkjet system to achieve multiple detections with an array of the sensors,” Ren claimed.
“The active area in a sensor, including source and drain contact area and gate detection area, is quite compact and can be minimized to less than 20 µm x 20 µm.”
Silicon transistors have also been developed for electronic biomarker detectors, but Ren chose GaN because it is much more chemically stable than silicon or GaAs. Approaches that use carbon nanotubes and nanowires made from silicon, In2O3, or ZnO are also in development.
“Nano-devices also have very good detection capability, sometimes even better than GaN HEMTs,” said Ren. “However, it may be difficult to achieve low cost and high throughput production for nanorods and nanotubes.”
This is not the first GaN based detector that Ren has made for medical diagnosis. His other devices can detect protein biomarkers for prostate cancer in urine, and glucose measurement that could be used to analyse breath samples for diabetes.
These detectors suggest some obvious commercial opportunities for the University of Florida beyond the tie-up with Nitronex, the specialist GaN HEMT manufacturer that employs five co-authors of the KIM-1 paper.
Ren and his colleagues hope to commercialize their technology and are currently discussing ways to exploit breath condensate based glucose detection with interested parties.
