Fabrication of 1D nanofluidic channels on glass substrate by wet etching and room-temperature bonding

In this paper, a simple and facile technique for fabricating one-dimensional (1D) glass nanofluidic chips was developed. Instead of using expensive nanolithography, the standard UV lithography and wet chemical etching technique was used to fabricate 1D nanochannels on a glass substrate. Smooth channel surfaces were obtained by adding HNO3 into conventional HF–NH4F etching solution. The calibrated etching rate of 3.6 nm min−1 was achieved using 1.5 × 10−2 mol L−1 HF–7.5 × 10−3 mol L−1 NH4F–7.5 × 10−3 mol L−1 HNO3 as etchant at 40 °C. Inter-day preparation gave a R.S.D. of 6.8% in channel depth. The substrate was bonded with a glass cover plate at room temperature. A minimum aspect ratio (depth to width) of 5.0 × 10−5 for the nanochannels was achieved. The channel depth before bonding was measured by an a-surface profilometer, and the depth uniformity of nanochannels after bonding was demonstrated by cross-section scanning electron microscopy (SEM) analysis. With this technique, we successfully fabricated a nanofluidic device integrating nanochannel with microchannels and demonstrated the ion enrichment-depletion phenomena.