Self-sensing nanopipette for liquid dispensing and AFM imaging

We present the design, fabrication, and characterization of a self-sensing nanopipette (SSN) that can dispense liquids and perform scanning probe nanolithography. The device consists of a legged hollow SiO
₂
microfluidic cantilever connected to an on-chip fluid reservoir. The cantilever has a Si
₃
N
₄
tip with a nozzle for fluid dispensing. The self-sensing capability is given by integrating gold piezoresistors on the legs, where the maximum strain is concentrated. The SSN has a resonance frequency of 122.185 kHz and a stiffness of 4.77 N/m, which are in agreement with the analytical and simulated values. The piezoresistors experienced a change in resistance of 0.35Ω for a cantilever deflection of 18.8 μm, leading to a gauge factor of 0.3. The dispensed liquid has an estimated volume in the range of tens of zeptolitres.