# US 10,309,728 B2 · Titanium-based thermal ground plane > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,728 B2 - Document ID: US10309728B2 - Status: Granted - Kind: B2 - Application number: 14/338,033 - Filed: 2014-07-22 - Published: 2014-11-13 - Granted: 2019-06-04 - Earliest claimed: 2008-07-21 - Assignees: The Regents of the University of California - Applicants: The Regents of the University of California - Inventors: Noel C. MacDonald; Carl D. Meinhart; Changsong Ding; Payam Bozorgi; Gaurav Soni; Brian D. Piorek - Web page: https://patentgrep.com/patent/US10309728B2 ## CPC - F28D 15/04: with tubes having a capillary structure - F28D 15/046: {characterised by the material or the construction of the capillary structure} - H10W 40/73: for cooling by change of state - Y10T 29/4935: Heat exchanger or boiler making - F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general) - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Titanium-based thermal ground planes are described. A thermal ground plane in accordance with the present invention comprises a titanium substrate comprising a plurality of pillars, wherein the plurality of Ti pillars can be optionally oxidized to form nanostructured titania coated pillars, and a vapor cavity, in communication with the plurality of titanium pillars, for transporting thermal energy from one region of the thermal ground plane to another region of the thermal ground plane. ## Claims ### Claim 1 A thermal ground plane, comprising: a wicking structure on a titanium substrate, the wicking structure comprising a plurality of microfabricated structures etched into the titanium substrate, wherein a pitch of the microfabricated structures is a distance from a center of one microfabricated structure to a center of a next neighboring microfabricated structure, and the microfabricated structures comprise titanium; a vapor cavity in communication with the wicking structure; a fluid contained within the wicking structure and the vapor cavity for transporting thermal energy between a hotter region of the thermal ground plane and a colder region of the thermal ground plane, wherein the hotter region is hotter than the colder region, the fluid is driven by capillary forces within the wicking structure, and the fluid comprises a liquid phase and a vapor phase; and the pitch of the microfabricated structures in a range between 5-500 micrometers, wherein the microfabricated structures include an etched roughness in a range of 1-1000 nanometers that enhances wetting performance of the wicking structure. ### Claim 2 (depends on 1) The thermal ground plane of claim 1, wherein the pitch in the colder region is different from the pitch in the hotter region. ### Claim 3 (depends on 2) The thermal ground plane of claim 2, wherein the pitch in the hotter region is smaller than the pitch in the colder region, such that a number density of the microfabricated structures in the hotter region is higher than in the colder region. ### Claim 4 (depends on 1) The thermal ground plane of claim 1, wherein a number density of the microfabricated structures varies. ### Claim 5 (depends on 1) The thermal ground plane of claim 1, wherein the microfabricated structures each have a height in a range of 5-200 micrometers and one or more spacings in a range of 1-500 micrometers. ### Claim 6 (depends on 1) The thermal ground plane of claim 1, wherein a pitch of the microfabricated structures is varied. ### Claim 7 (depends on 6) The thermal ground plane of claim 6, where the pitch of the microfabricated structures is smaller in the hotter region compared to the cooler region such that capillary forces are increased in the hotter region. ### Claim 8 (depends on 1) The thermal ground plane of claim 1, wherein the microfabricated structures comprise sidewalls defining channels. ### Claim 9 A thermal ground plane, comprising: a first titanium substrate and a second titanium substrate; a wicking structure etched into the first titanium substrate; a vapor cavity etched into the second titanium substrate, wherein the vapor cavity is in communication with the wicking structure; a fluid contained within the wicking structure and the vapor cavity for transporting thermal energy between a hotter region of the thermal ground plane and a colder region of the thermal ground plane, wherein the hotter region is hotter than the colder region, the fluid is driven by capillary forces within the wicking structure, and the fluid comprises a liquid phase and a vapor phase, wherein the wicking structure has a height ranging from 5 to 200 microns, a pitch ranging from 5-500 microns, and one or more spacings ranging between 1-500 micrometers; and wherein the wicking structure includes an etched roughness of 1-1000 nm. ### Claim 10 (depends on 9) The thermal ground plane of claim 9, wherein the first titanium substrate and the second titanium substrate are welded together to form a hermetically-sealed thermal ground plane. ### Claim 11 (depends on 10) The thermal ground plane of claim 10, wherein the first titanium substrate and the second titanium substrate are laser welded together to form a hermetically-sealed thermal ground plane. ### Claim 12 (depends on 9) The thermal ground plane of claim 9, wherein the wicking structure comprises sidewalls defining channels. ### Claim 13 (depends on 5) The thermal ground plane of claim 5, wherein the pitch, height, and spacings are such that the wicking structure has a thermal conductivity of at least 350 W/m-K.