Liquid metal ink
A method for forming a conductive trace on a substrate. A metallic liquid is mixed with a solvent to produce a metallic liquid mixture. The metallic liquid mixture is stimulated to produce a colloidal suspension of discrete metallic liquid particles surrounded by the solvent. The colloidal suspension is aerosolized with a carrier gas, and passed through a nozzle to deposit the discrete metallic liquid particles onto the substrate. The deposited discrete metallic liquid particles are annealed, thereby producing the conductive trace. The conductive trace has a substantially contiguous core of the metallic liquid within a substantially non-electrically conductive solid skin that substantially bounds the liquid core.
1. A method for forming a conductive trace on a substrate, the method comprising the steps of:
combining a metallic liquid comprising gallium with a solvent to produce a metallic liquid mixture,
stimulating the metallic liquid mixture to produce a colloidal suspension of discrete metallic liquid particles surrounded by the solvent,
aerosolizing colloidal suspension with a carrier gas, and
passing the aerosolized colloidal suspension through a nozzle to deposit the discrete metallic liquid particles onto the substrate, and
annealing the deposited discrete metallic liquid particles,
thereby producing the conductive trace, where the conductive trace has a contiguous core of the metallic liquid within a solid skin having an electrical conductivity of less than 1 S/cm that bounds the liquid core.
2. The method of claim 1 , wherein the metallic liquid comprises an alloy of gallium and indium.
3. The method of claim 1 , further comprising annealing the conductive trace within a desired temperature range, a desired time range, and a desired pressure range.
4. The method of claim 3 , wherein the desired temperature range is no less than about 500 centigrade.
5. The method of claim 3 , wherein the desired time range is no less than about five minutes.
6. The method of claim 3 , wherein the desired pressure range is from about 10′ millibar to about one atmosphere.
7. The method of claim 1 , wherein stimulating the metallic liquid mixture comprises ultrasonic vibration of the mixture.
8. The method of claim 1 , wherein the solvent comprises absolute ethanol.
9. The method of claim 1 , wherein the solvent comprises dimethyl sulfoxide.
10. The method of claim 1 , wherein the solvent comprises a mixture of absolute ethanol and dimethyl sulfoxide.
11. The method of claim 10 , wherein the mixture of absolute ethanol to dimethyl sulfoxide is a ratio of about three to one, respectively.
12. The method of claim 1 , wherein the step of annealing the metallic material is performed in a non-oxidizing environment having a pressure of 1×10 −6 mBar or less.
13. The method of claim 1 , wherein the non-electrically conductive solid skin comprises an oxide of the metallic material that forms in an oxygen-containing environment.
14. A method for forming a conductive trace, the method comprising the steps of:
aerosol jetting a metallic material on a substrate, where the metallic material is a colloidal suspension of a eutectic mixture of gallium and indium in a solvent base of three parts absolute ethanol to one part dimethyl sulfoxide,
annealing the metallic material within a desired temperature range of no less than about 500 centigrade, a desired time range of no less than about five minutes, and a desired pressure range of from about 10 −7 millibar to about one atmospheric,
thereby producing the conductive trace, where the conductive trace has a contiguous, electrically conductive liquid core within a non-electrically conductive solid skin having an electrical conductivity of less than 1 S/cm that substantially bounds portions of the liquid core that have been exposed to oxygen, wherein the non-electrically conductive solid skin comprises an oxide of the metallic material.