A complex of the induction magnetic field two-way (nano)transducers of the different physical values for both the external and implantable devices for a wide range of applications are summarized.

Patent Pending An AC current sensor produces a voltage output that is proportional to the current passing through the sensor. The sensor responds like a resistor in that the AC voltage is proportional to the AC current but the sensor offers complete electrical isolation. A closed loop technique using a magnetic core and feedback coil can be implemented to balance the magnetic flux from the current being sensed [1]. The most sensitive of all instruments for measuring a magnetic field (MF) at low frequencies (<1 Hz) is the superconducting quantum interference device (SQUID). It is based on the remarkable interactions of electric currents and MFs observed when certain materials are cooled below a superconducting transition temperature. The SQUID ring essentially serves as a very precise ammeter for measuring the current in the pickup coil (PC). Thus, the device has three superconducting components: the SQUID ring itself, the radio-frequency coil, and the large antenna loop. Since then there has been a range of new approaches to create nanoSQUIDs, including the use of carbon nanotubes as proximity junctions. When a SQUID is reduced to the nanometre-scale, the thermal noise limitations on SQUID sensitivity are reduced by lowering its inductance and capacitance. NanoSQUIDs could be used for the metrology of various physical parameters to the quantum limit [2]. Alternatively, an attempt to generalize the current knowledge of passive MF transducers— SQUID and induction sensors (MAFCOPS)— and to incorporate elements of both designs in order to find a way to improve their performance data by creating, in theory, a combined transducer— superconducting induction magnetometer (SIM) was done [3]. The proposed magnetometer circuit consists of both room-temperature or cooled (up to superconductive) PC and a superconducting field-effect transistor (SuFET). A solid-state ion bipolar junction transistor, the pnp-IBJT, can be constructed in a similar way as its pnp-semiconductor counterpart. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented [4]. Moreover, a SuFET based neurotransducer with carbon nanotubes (CNT) or PC kind of input circuit for the nerve and neuron impulse has been designed. It combines the current nature of electronic and ionic signals with ambient-temperature PC and zero resistance input of the SuFET device in order to obtain most advantageous current transducer (SuFETTr). Electronic or ionic currents in conductors or axons respectively, passing through the SuFET’s channel induce the output voltage on its gate [5]. An organic field effect transistor (OFET) has shown very interesting performances, with typical values of the electronic parameters very similar to those of planar devices. Self-assembled molecular nanowires (NWs), allowing good electrical transport with low resistivity. Finally, FET with single- and doublewire channels (NWFET) were fabricated to give some indication of the potential application of the molecular wires. A number of the sensing structures with the improved characteristics, as a result of the combination between flexible PCs and OFETs, are being designed: a wide-band MF transducer with an ultimate sensitivity, non-contact passive flowmeters of the volume flow of substances and tissues, acoustical receiver/generator which employing Meissner effect, a scanning and sounding nano-microscop, and an EM transistor/memristor [6].