The new microscopic sensor made on the basis of modern silicon transistors allows to trace in real time a state of health, analyzing a chemical composition of the liquids, such as sweat emitted by a body of the person. The high sensitivity of such sensor combined with the electronics which is strengthening and carrying out rather difficult processing of signals will allow to create small-sized self-contained medical units which by means of wireless technologies will carry out continuous round-the-clock monitoring of a state of health of the person.
The new sensor is development of Laboratory of nanoelectronic Nanoelectronic Devices Laboratory devices (Nanolab) of the Swiss federal polytechnical university of Lausanne (Swiss Ecole Polytechnique Federale de Lausanne, EPFL), it represents the first step on the way to creation of the diagnostic device which can be pasted to the patient’s body practically in any his place as a small slice of a transparent plaster.
“Ionic balance in the liquids emitted by a body of the person comprises the mass of information on a state of his health” – Adrian Ayonesku (Adrian Ionescu), the director of Nanolab tells, – “Our device allows to find not only an indicator of pH, but also even the most insignificant deviations of concentration of charged particles of different types in liquid. Besides we can trace the facts of emergence of some electric neutral molecules of proteins that expands functionality of our sensor”.
The basis of the sensor is made by the silicon FinFET transistors having almost same structure, as well as the transistors used by the Intel company in the most modern microprocessors. But, over the transistor researchers laid the microchannel via which the tiny stream of liquid which ionic analysis carries out the transistor sensor flows. When molecules and ions pass through area of the electronic channel of the transistor, their electric charge interferes with operation of the semiconductor device, changing the electric current flowing through it.
Within the device created by Swisses are not only transistors sensors, in close proximity to them are created the electronic schemes which are carrying out preliminary strengthening and normalization of signals. The design of the device has multilayered structure which is protected by additional elements from direct contact with conducting liquid. “In such systems usually use the separate sensors and electronic schemes strengthening and processing signals” – Sara Rigeynt (Sara Rigante) tells, – “All these elements are in our sensor nearby that guarantees that the signal will not be distorted or broken. And it, in turn, allows to take stable and high-precision measurements”.
Thanks to the small size of the transistor, about 20 nanometers that is one thousand times less than thickness of a human hair, become possible creation of the whole network of such sensors transistors on one chip. Each of transistors can be focused on detecting of ions or molecules of strictly certain type that will also allow to increase the accuracy of the performed measurements.
“In the field of creation of biosensors the intensive researches directed on introduction of nanotechnologies of various types in them in such sensors are conducted in every way try “to push” nanoconductors from materials of various types, a decanter and carbon nanotubes. But, such technologies based on materials and decisions unchecked up to the end very often work unstably and they are unsuitable for mass application” – Adrian Ayonesku tells, – “In a case with our sensor we deal with standard CMOS technologies, opportunities and which accuracy of production provide stability of characteristics of FinFET-transistors with a “liquid” lock. And it will allow to make such identical transistors in millions and in billions of pieces”.
Now the sensor created by the Swiss scientists works with a liquid stream which is created by the tiny micropump. But researchers already started working on development of a new design of the channel of the sensor in which liquid will move under the own steam under the influence of forces of a superficial tension.