The announcement out of UC Berkeley of the construction of a nanofluidic
transistor offers further evidence that the analysis of cells and their associated DNA will become more systematic in the
future. As well it also portends the coming of bioelectronic systems, which could integrate living cells, DNA and silicon
electronic technology to work together to form hybrid thinking machines, also referred to as molecular processors.
The nanofluidic transistor constructed, also referred to as unipolar
ionic field-effect transistor, similar in name to a semiconductor MOSFET(metal oxide semiconductor field effect transistor),
shut off potassium ion flow through water - analogous to a MOSFET shutting off electron flow. The tiny device structure consisted
of a 35 nanometer high channel between two silicon dioxide plates. However, unlike present day MOSFETs, which can shut off
current flow with a 1 volt potential, it took a voltage of 75 volts to close the channel to the passage of the potassium ions
– a voltage that would make it difficult to integrate a dense system-on-a-chip of integrated nanotubes to enable the
mass-scale separation of negative and positive ions.
The system eventually has the potential to act as a virtual
valve, fundamental to a larger integrated system, which would screen for specific diseases. The Berkeley team visualizes
a disease screening device that is based on a nanotube coated with antigens. When antibodies that are specific to a
specific disease flow through the antigen lined nanotube, the antigen and antibody would attract, resulting in the blocking
the flow of liquid through the tube and changing the electrical current – indicating the presence of a specific disease.
The work at Berkeley has been supported by the National Cancer Institute
as a way to devise a test that can detect the presence of prostrate cancer. However it is also seen as the first step towards
integration of silicon with floating molecules, enabling a decisively different way to perform mathematically intensive computations.
