FABRICATION OF A SCALABLE QUANTUM SENSING DEVICE THROUGH PRECISELY PROGRAMMABLE PATTERNING SPIN DEFECTS ON UNIVERSAL SUBSTRATES
A method of fabricating a nitrogen-vacancy (NV) center quantum sensing device based on electrohydrodynamic (EHD) printing. A nanopipette with an aperture at one end is filled with nanodiamond suspension ink so the ink is present in a meniscus at The aperture, the nanodiamond suspension ink comprises nanodiamonds and solvent. The nanopipette is supported above a substrate having a back electrode. A DC is applied pulse between the nanopipette and the back electrode so as to generate an electrostatic attractive force resulting in the ejection of nano-diamond-laden droplets with sub-attoliter volume. The droplet lands on the substrate and is allowed to dry due to solvent evaporation. Using the method, the control of the number of printed nano-diamonds is at will, attaining single-particle level precision. This printing approach, therefore, enables printing NV center arrays with a controlled number directly on the substrate without any lithographic process.
1 . A method of fabricating a nitrogen-vacancy (NV) center quantum sensing device based on electrohydrodynamic (EHD) printing, comprising the steps of:
providing a nanopipette with an aperture at one end and filled with nanodiamond suspension ink so the ink is present in a meniscus at an end of the aperture, the nanodiamond suspension ink comprising nanodiamonds and solvent;
supporting the nanopipette apart from a substrate having a back electrode;
applying a DC pulse between the nanopipette and the back electrode so as to generate an electrostatic attractive force between the meniscus at the nanopipette and the substrate, resulting in the ejection of nano-diamond-laden droplets with sub-attoliter volume;
allowing the droplet to land on the substrate; and
allowing the droplet to dry due to solvent evaporation.
2 . The method of forming nanodiamonds according to claim 1 wherein the nanopipette is made of glass.
3 . The method of forming nanodiamonds according to claim 1 wherein the nanodiamonds in the nanodiamond suspension ink are carboxylated.
4 . The method of forming nanodiamonds according to claim 1 wherein nanodiamonds in the nanodiamond suspension ink comprises 1˜4 NV centers per particle.
5 . The method of forming nanodiamonds according to claim 1 wherein the nanodiamond suspension ink has an ion strength of 13 μM or less.
6 . The method of forming nanodiamonds according to claim 1 wherein the nanodiamond suspension ink is prepared by adding TX100.
7 . The method of forming nanodiamonds according to claim 1 wherein the nanopipette is supported at a fixed separation from a substrate.
8 . The method of forming nanodiamonds according to claim 1 wherein the nanodiamonds in the nanodiamond suspension ink has a concentration of 1-4 μg/mL.
9 . The method of forming nanodiamonds according to claim 1 wherein the substrate is supported by a three-axis stepping motorized stage that keeps the nanopipette and substrate at a fixed separation, but allows the substrate to be moved with respect to the nanopipette so that an array of droplets can be printed on the substrate.
10 . The method of forming nanodiamonds according to claim 1 wherein the back electrode is an indium tin oxide (ITO)-coated glass plate and the substrate is silicon.
11 . The method of forming nanodiamonds according to claim 1 wherein the DC pulse had a voltage amplitude of 350V or more and a length of at least 5 ms.