Figure 1.

Principle and design of the nanofluidic biosensing platform. (a) Electrostatic effect-based nanofluidic biosensing does not work in normal physiological conditions due to the suppression of the Debye length at high ionic concentrations. (b) Principle of ion concentration polarization coupled nanofluidic crystal for biosensing. (c) SEM image of the central sensing region on the silicon substrate, a magnified view of the nanofilter array, and bright-field microscope photo of the chip after anodic bonding, which shows the micropatterned Ag/AgCl electrode pair on the glass substrate. (d) Filling of nafion resin by capillary force. (e) Assembled nanofluidic crystal in the central region. Dual-layer packing allows the packing of nanoparticles smaller than the nanofilter cutoff size (400 nm), as described in Materials and Methods.