Microdevice for the In Situ Detection of Particles of Interest in a Fluid Medium and Operating Method

Method of detecting particles of interest in situ in a fluid medium comprising the steps of:

• providing a device comprising:
• i) a nanowire configured for interacting with the particles of interest, having a length (L) and a width (Z), said nanowire being suspended between two anchors and having a mechanical resonance frequency (ω0), the anchors defining a source and a drain, the source being connected to a first voltage generator (generating an AC voltage with a first angular frequency (ωLO) and the drain being connected to a voltage generator for generating a DC voltage (VSD), in order to generate a first input signal;
• ii) an excitation electrode, placed laterally and facing the nanowire, said first electrode being connected to a second voltage generator for generating an AC voltage (νRF) with a second angular frequency (ωRF), in order to generate a second input signal;
• and
• iii) a measurement electrode placed laterally and facing the nanowire, on the opposite side from the excitation electrode relative to the nanowire and generating an output signal representative of the particles of interest;
• supplying the source with a carrier AC voltage (νLO), having a first angular frequency (ωLO) different from the mechanical resonance frequency (ω0) of the nanowire;
• supplying the drain with a DC voltage (VSD);
• supplying the excitation electrode with a control AC voltage (νRF), having a second angular frequency (ωRF) equal to the sum of the first angular frequency (ωLO) and the mechanical resonance frequency (ω0) of the nanowire;
• depositing at least one particle of interest on the nanowire;
• and
• detecting a current (Iout) output with the measurement electrode.