Question

1. What types of chemical compounds can be detected using MOSFETs?

2. One of the possible biosensors is the “DNAFET.” How does it work?

3. What are the future impacts on health and medicine of embedded biosensors?

Answer 1

1. MOSFETs with a bio-sensitive layer are used to specifically detect bio-molecules such as nucleic acids and proteins.so these are used in medical field to sense DNAs ,RNAs , enzymes, oligonucleotides etc. Also antibody and its fragments are the most popular biological entities employed as bio-receptors because they can specifically bind with targeted molecules (antigen) in a familiar reaction so-called immunoassay to produce electrical signal readable by tranducers.

2 . A DNAFET (DNA field-effect transistor) is a field-effect transistor which uses the field-effect due to the partial charges of DNA molecules to function as a biosensor.

The structure of DNAFETs is similar to that of MOSFETs. The exception is that the gate structure which, in DNAFETs, is replaced by a layer of immobilized single-stranded DNA molecules which act as surface receptors. When complementary DNA strands hybridize to the receptors, the charge distribution near the surface changes. This in turn modulates current transport through the semiconductor transducer. By measuring this current flow we can detect DNA molecules.

3.

DNAFETs have robust future impacts on health and medicine of embedded biosensors.

Arrays of DNAFETs can be used for detecting single nucleotide polymorphisms which are causing many hereditary diseases and for DNA sequencing.

Their main advantage of DNAFETs compared to optical detection methods in common use today is that they do not require labeling of molecules

DNAFETs work continuously and (near) real-time. DNAFETs are highly selective since only specific binding modulates charge transport.

This technology is now started to use in fast identification of viral infections such as ebola and HIV and many developments are going to happen in near future.