Could
electronic components made from human blood be the key to creating
cyborg interfaces? Circuitry that links human tissues and nerve cells
directly to an electronic device, such as a robotic limb or artificial
eye might one day be possible thanks to the development of biological
components.
Writing
in the International Journal of Medical Engineering and Informatics, a
team in India describes how a “memristor” can be made using human blood.
Memristors were a theoretical electronic component first suggested in
1971 by Berkeley electrical engineer Leon Chua and finally developed in
the laboratory by scientists at Hewlett Packard using titanium dioxide
in 2008. A memristor is a passive device, like a resistor, with two
terminals but rather than having a fixed electrical resistance, its
ability to carry a current changes depending on the voltage applied
previously; it retains a memory of the current, in other words.
There
are countless patents linking the development of memristors to
applications in programmable logic circuits, as components of future
transistors, in signal processing and in neural networks. S.P. Kosta of
the Education Campus Changa in Gujarat and colleagues have now explored
the possibility of creating a liquid memristor from human blood. In
parallel work they are investigating diodes and capacitors composed of
liquid human tissues.
They
constructed the laboratory-based biological memristor using a 10 ml
test tube filled with human blood held at 37 Celsius into which two
electrodes are inserted; appropriate measuring instrumentation was
attached. The experimental memristor shows that resistance varies with
applied voltage polarity and magnitude and this memory effect is
sustained for at least five minutes in the device.
Having
demonstrated memristor behavior in blood, the next step was to test
that the same behavior would be observed in a device through which blood
is flowing. This step was also successful. The next stage will be to
develop a micro-channel version of the flow memristor device and to
integrate several to carry out particular logic functions. This research
is still a long way from an electronic to biological interface, but
bodes well for the development of such devices in the future.
