Nanofibers and methods of making same and using same in humidity sensors
View Patent ↗A self-cleaning humidity sensor based on Mg 2+ /Na + -doped TiO 2 nanofiber mats is provided. Examples show the response and recovery characteristic curves for ten circles with the RH changing from 11% to 95%. The nanofibers are manufactured by mixing together a metal salt comprising titanium, a magnesium compound, a sodium compound, and a high molecular weight material to form a mixture, electrospinning the mixture to form composite nanofibers, and calcining the composite nanofibers to yield a TiO 2 nanofiber material doped with magnesium and sodium.
1. A method for making a nanofiber for use in a humidity sensor, comprising:
providing a titanium compound;
mixing the titanium compound with a magnesium compound, a sodium compound, and a high molecular weight polymer material to form a mixture;
electrospinning the mixture to form composite nanofibers; and
calcining the composite nanofibers to yield a TiO 2 nanofiber material doped with magnesium and sodium.
2. A method as in claim 1 , wherein the doped TiO 2 nanofiber material forms a nanofiber mat.
3. A method as in claim 1 , wherein the high molecular weight polymer material comprises at least one of polyvinyl alcohol or polyvinyl pyrrolidone.
4. A method as in claim 1 , wherein the high molecular weight polymer material has a molecular weight of about 300,000 or greater.
5. A method as in claim 1 , wherein the high molecular weight polymer material has a molecular weight of about 1,000,000 or greater.
6. A method as in claim 1 , further comprising sonicating the TiO 2 nanofiber material.
7. A method as in claim 1 in which the composite nanofibers are calcined at a temperature of about 500° C. or greater.
8. A method as in claim 1 in which the composite nanofibers are calcined at a temperature of about 600° C. or greater.
9. A method as in claim 1 in which the composite nanofibers are calcined at a temperature in a range from about 500° C. to about 650° C.
10. A method for making a humidity nanosensor comprising depositing the TiO 2 nanofiber material manufactured according to the method of claim 1 onto an electrode configured to sense humidity in combination with the TiO 2 nanofiber material.
11. A method of detecting the relative humidity of a gaseous mixture comprising exposing a humidity sensor manufactured according to the method of claim 10 to a gaseous mixture that includes water vapor and detecting a change in an electrical output of the humidity nanosensor.
12. A method for making a humidity nanosensor as in claim 10 , wherein the TiO 2 nanofiber material is formed as a mat on the electrode.
13. A method for making a humidity nanosensor as in claim 12 , wherein the electrode is an interdigital electrode.
14. A method for making a humidity nanosensor as in claim 10 , wherein the electrode includes a noble metal.
15. A method as in claim 1 , wherein the TiO 2 nanofiber material includes nanofibers having a width in a range about 10 nm to about 600 nm.
16. A method as in claim 1 , wherein the TiO 2 nanofiber material includes nanofibers having a width in a range about 50 nm to about 300 nm.
17. A method as in claim 1 , wherein the titanium compound is a tetravalent organometallic compound of titanium, the magnesium compound is an inorganic salt of magnesium, and the sodium compound is an organometallic sodium compound.
18. A method as in claim 1 , wherein the tetravalent organometallic compound of titanium comprises tetrabutyl titanate, the inorganic salt of magnesium comprises magnesium chloride, and the organometallic sodium compound comprises dioctyl sulfosuccinate sodium.
19. A method for making a nanofiber for use in a humidity sensor, comprising:
providing tetrabutyl titanate;
mixing the tetrabutyl titanate with a magnesium compound, a sodium compound, and a high molecular weight polymer material to form a mixture;
electro spinning the mixture to form composite nanofibers; and
calcining the composite nanofibers to yield a TiO 2 nanofiber material doped with magnesium and sodium.
20. A method for making a nanofiber for use in a humidity sensor, comprising:
providing a tetravalent organometallic compound of titanium;
mixing the tetravalent organometallic compound of titanium with an inorganic salt of magnesium, an organometallic sodium compound, and a high molecular weight polymer material to form a mixture;
electro spinning the mixture to form composite nanofibers; and
calcining the composite nanofibers to yield a TiO 2 nanofiber material doped with magnesium and sodium.