Researchers at UC Santa Barbara have surpassed the fundamental limits of a conventional Field-Effect-Transistor (FET) by designing a Tunnel-FET (T-FET) sensor that is faster and four orders of magnitude more sensitive, opening doors to a new generation of ultra-sensitive biosensors that could perform instant point-of-care disease diagnostics.
Biosensors based on conventional FETs have been gaining momentum in the medical, forensic, and security industries since they are cost-effective compared to optical detection procedures. Such biosensors allow for scalability and label-free detection of biomolecules -- removing the step and expense of labeling target molecules with fluorescent dye.
The principle behind any FET-based biosensor is similar to the FETs used in digital circuit applications, except that the physical gate is removed and the work of the gate is carried out by charged versions of the biomolecules it intends to detect. For immobilizing these biomolecules, the dielectric surface enclosing the semiconductor is coated with specific receptors, which can bind to the target biomolecules — a process called conjugation.
The key concept behind the new device relies on quantum physics — a current injection mechanism that leverages biomolecule conjugation to bend the energy bands in the channel region, leading the quantum-mechanical phenomenon of band-to-band tunneling, said Deblina Sarkar, PhD student at UC Santa Barbara and lead author of the paper.
