Integrated electric current sensors

A capacitance sensor provides information on sohds concentration in the target space between its two electrodes. When a voltage E is applied between the electrodes, an equilibrium charge Q is accumulated in them. The charge can be determined by integrating the measured electric current between the electrodes over time. Capacitance is the ratio QjE. For a set of two parallel plates of area A, separated by a homogenous dielectric of thickness d, the capacitance is given by... 

Magetoresistivity-based sensors, which are based on a resistivity change induced by a magnetic field, have found wide application in industry. However, such sensors are usually fabricated of metals and hence it is difficult to integrate them with conventional semiconductor devices. To develop magetoresistive sensors in semiconductors, one of the key problems is how to effectively inject spin-polarized electrons into paramagnetic semiconductors. The spin Hall effect (SHE), which involves a spin-current transverse to an applied electric field, " potentially provides a new way to resolve this issue. 

Fig. 4 High-sensitivity electrical measurements can be made by designing analytical instrumentation with suitable electrical shielding close to the single cell measurement chamber. The device shown has an integrated single cell analytical chamber, similarto the type shown in Fig. 3, together with shielded amplifiers and a PC interface. The setup is common to the measurements from a family of single sensors, currently being produced in the author s laboratories.

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