# US 12,225,638 B2 · Integrated microheater array for efficient and localized heating of magnetic nanoparticles at microwave frequencies > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,225,638 B2 - Document ID: US12225638B2 - Status: Granted - Kind: B2 - Application number: 17/650,982 - Filed: 2022-02-14 - Published: 2022-08-18 - Granted: 2025-02-11 - Earliest claimed: 2021-02-12 - Assignees: William Marsh Rice University - Applicants: William Marsh Rice University - Inventors: Yingying Fan; Qingbo Zhang; Linlin Zhang; Gang Bao; Taiyun Chi - Web page: https://patentgrep.com/patent/US12225638B2 ## CPC - H05B 3/265: {the insulating base being an inorganic material, e.g. ceramic (H05B3/262 takes precedence)} - H05B 6/64: Heating using microwaves {(containers, packaging elements or packages specially adapted to be heated by microwaves B65D81/3446)} - H05B 2214/04: Heating means manufactured by using nanotechnology - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract An microheater array system includes an integrated microheater array configured to generate a localized heat and having a plurality of pixels. Each pixel includes: an inductor; a stacked oscillator configured to generate a magnetic field at microwave frequencies with tunable intensity and frequency; and an electro-thermal loop. The microheater array system may further include a plurality of magnetic nanoparticles (MNPs). ## Claims ### Claim 1 A microheater array system comprising: an integrated microheater array configured to generate a localized heat, having a plurality of pixels, wherein each pixel comprises: an inductor; a stacked oscillator configured to generate a magnetic field at microwave frequencies with tunable intensity and frequency; and an electro-thermal loop, wherein the stacked oscillator comprises a plurality of transistors connected in series, and a biasing voltage, a biasing resistor, and an external gate capacitor are applied to each transistor. ### Claim 2 (depends on 1) The microheater array system according to claim 1, wherein the electro-thermal loop is configured to regulate a local temperature distribution. ### Claim 3 (depends on 2) The microheater array system according to claim 2, wherein the electro-thermal loop is configured to monitor the localized heat and provide feedback to the stacked oscillator to configure an output of the stacked oscillator. ### Claim 4 (depends on 1) The microheater array system according to claim 1, wherein the microwave frequencies generated by the magnetic field are from 0.3 to 300 GHz. ### Claim 5 (depends on 1) The microheater array system according to claim 1, wherein a spatial resolution defined by a size of the pixels is less than 1 mm. ### Claim 6 (depends on 1) The microheater array system according to claim 1, wherein the localized heat increases a local temperature to at least 43° C. ### Claim 7 (depends on 1) The microheater array system according to claim 1, wherein both a drain-to-source voltage (Vds) and a drain-to-gate voltage (Vdg) for different transistors are close to one another and within a breakdown limit. ### Claim 8 (depends on 1) The microheater array system according to claim 1, wherein the stacked oscillator comprises a tail transistor connected to a source terminal of a bottom of the transistors wherein a gate of the tail transistor is used to control a dc power consumption and output power of the stacked oscillator. ### Claim 9 (depends on 1) The microheater array system according to claim 1, wherein the stacked oscillator includes a capacitor bank. ### Claim 10 (depends on 1) The microheater array system according to claim 1, wherein the stacked oscillator in each pixel occupies one inductor without additional RF amplifiers. ### Claim 11 (depends on 1) The microheater array system according to claim 1, wherein the stacked oscillator has a voltage swing of at least 18 Vpp. ### Claim 12 (depends on 1) The microheater array system according to claim 1, wherein a simulated dc-to-RF efficiency of the stacked oscillator is at least 45%. ### Claim 13 (depends on 1) The microheater array system according to claim 1, further comprising a plurality of magnetic particles having a having ferromagnetic resonance at resonant microwave frequencies, wherein the microwave frequencies comprise the resonant frequencies; and wherein the electro-thermal loop is configured to monitor the localized heat, wherein the localized heat is generated by the magnetic nanoparticles in response to the magnetic field. ### Claim 14 (depends on 13) The microheater array system according to claim 13, wherein the magnetic particles are magnetic nanoparticles (MNPs). ### Claim 15 (depends on 14) The microheater array system according to claim 14, wherein the MNPs comprise nanostructured or amorphous Fe3O4. ### Claim 16 (depends on 13) The microheater array system according to claim 13, wherein the magnetic particles are contained in a layer. ### Claim 17 (depends on 16) The microheater array system according to claim 16, wherein the layer comprises a solution. ### Claim 18 (depends on 16) The microheater array system according to claim 16, wherein the layer comprises a membrane. ### Claim 19 A method for generating localized heat using an integrated microheater array device, comprising: disposing magnetic nanoparticles on a microheater array, wherein the microheater array comprises a plurality of pixels, each pixel comprises an inductor, a stacked oscillator, and an electro-thermal loop; generating, by the stacked oscillator, a magnetic field at microwave frequencies with tunable intensity and frequency; monitoring a localized heat generated by magnetic nanoparticles in response to the magnetic field; and providing feedback through the electro-thermal loop to configure an output power of the stacked oscillator, wherein the stacked oscillator comprises a plurality of transistors connected in series, and a biasing voltage, a biasing resistor, and an external gate capacitor are applied to each transistor.