Minimally-invasive tissue ablation using high contrast electric fields

Abstract

Described embodiments include a system and a method. A system includes an electromagnetic structure having a surface and a radiofrequency electromagnetic field source. The field source includes electronically controllable, artificially structured electromagnetic unit cells configured to create quasi-static electromagnetic fields within the electromagnetic structure. Each unit cell is responsive to a control signal. A selector circuit selects a quasi-static electromagnetic field pattern creating a high contrast electric field in a subwavelength electromagnetic cavity and is defined by the surface of the electromagnetic structure and an exterior surface of a perturbing object. The high contrast electric field has a power density that is localized to a volume adjoining the exterior surface of the perturbing object. A field pattern implementation circuit generates the control signal assigning electromagnetic field characteristic to each of the electromagnetic unit cells. The assigned radiofrequency electromagnetic field characteristics collectively creating the selected quasi-static electromagnetic field pattern.

What is claimed is: 
     
         1 . A system comprising:
 a perturbing object configured to be implanted within or proximate to a target tissue of a living vertebrate subject;   an electromagnetic structure including a radiofrequency electromagnetic field source, the radiofrequency electromagnetic field source including at least two electronically controllable, artificially structured electromagnetic unit cells configured to create quasi-static radiofrequency electromagnetic fields, each unit cell respectively responsive to a control signal;   a selector circuit configured to select a quasi-static electromagnetic field pattern creating a radiofrequency electric field in a subwavelength electromagnetic cavity defined at least in part by the electromagnetic structure and an exterior surface of the perturbing object; and   a field pattern implementation circuit configured to:
 generate the control signal to which each unit cell is respectively responsive, the control signal assigning a respective radiofrequency electromagnetic field characteristic to each of the at least two electronically controllable, artificially structured electromagnetic unit cells; and 
 transmit the control signal to the at least two electronically controllable, artificially structured electromagnetic unit cells, the respective assigned radiofrequency electromagnetic field characteristics collectively causing the at least two electronically controllable, artificially structured electromagnetic unit cells to create the selected quasi-static radiofrequency electromagnetic field pattern within the subwavelength electromagnetic cavity. 
   
     
     
         2 . The system of  claim 1 , wherein the electromagnetic structure includes an electromagnetic cavity structure. 
     
     
         3 . The system of  claim 1 , wherein the electromagnetic structure is electrically insulated from the living vertebrate subject. 
     
     
         4 . The system of  claim 1 , wherein the electromagnetic structure includes at least one of an open electromagnetic cavity structure, a leaky open electromagnetic cavity structure, or a resonant open electromagnetic cavity structure. 
     
     
         5 . The system of  claim 1 , wherein the electromagnetic structure supports at least two quasistatic radiofrequency electromagnetic field patterns, where the at least two quasi-static radiofrequency electromagnetic field patterns are resonant modes or eigenmodes of the electromagnetic cavity structure. 
     
     
         6 . The system of  claim 1 , wherein a first portion of the surface includes the radiofrequency electromagnetic field source and a second portion of the surface includes a passive surface, the passive surface including at least one of a conductive material, a composite medium, an effective medium, a metamaterial, a metasurface, a semiconductor material, or an electromagnetically anisotropic surface. 
     
     
         7 . The system of  claim 1 , wherein the radiofrequency electromagnetic field source is configured to generate a near-field region electromagnetic field in at least a portion of the 1 Megahertz (MHz)-1 Gigahertz (GHz) range. 
     
     
         8 . The system of  claim 1 , wherein each artificially structured electromagnetic unit cell is randomly accessible. 
     
     
         9 . The system of  claim 1 , wherein each artificially structured electromagnetic unit cell of the at least two artificially structured electromagnetic unit cells includes a respective controller configured to regulate electromagnetic fields generated by the respective electromagnetic unit cell in response to the control signal, wherein the controller is configured to regulate a phase, polarization, wave impedance, or amplitude of electromagnetic fields generated by the respective electromagnetic unit cell. 
     
     
         10 . The system of  claim 1 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern responsive to real-time data received from a radiofrequency electromagnetic field sensor. 
     
     
         11 . The system of  claim 1 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern responsive to (i) a parameter of the subwavelength electromagnetic cavity, and (ii) a parameter of the perturbing object. 
     
     
         12 . The system of  claim 11 , wherein the parameter of the subwavelength electromagnetic cavity includes a resonant frequency of the subwavelength electromagnetic cavity. 
     
     
         13 . The system of  claim 11 , wherein the parameter of the perturbing object includes at least one of a shape, a dimension, a surface impedance, a dielectric permittivity, or a magnetic permeability of the perturbing object. 
     
     
         14 . The system of  claim 1 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern in response to a model-based estimation of an electric field power density localized to the volume adjoining the exterior surface of the perturbing object. 
     
     
         15 . The system of  claim 1 , wherein the selected quasi-static electromagnetic field pattern includes a selected quasi-static electromagnetic field pattern creating a radiofrequency electric field having a power density localized to a tissue ablation volume adjoining the exterior surface of the perturbing object. 
     
     
         16 . The system of  claim 1 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern in response to indicia of a core temperature of the living vertebrate subject. 
     
     
         17 . The system of  claim 1 , wherein the exterior surface of the perturbing object has a conductivity greater than 4.0 Siemens per meter at 20° C. 
     
     
         18 . A system, comprising:
 a three-dimensional domain having a surface and a radiofrequency electromagnetic field source;   a perturbing object configured to be implanted within or proximate to a target tissue of a living vertebrate subject;   the radiofrequency electromagnetic field source including at least two electronically controllable electromagnetic unit cells configured to create quasi-static radiofrequency electromagnetic fields within the three-dimensional domain;   a selector circuit configured to select a quasi-static electromagnetic field pattern creating a radiofrequency electric field in an electromagnetic cavity defined at least in part by the surface of the three-dimensional domain and an exterior surface of the perturbing object; and   a field pattern implementation circuit configured to:
 generate a control signal assigning a respective radiofrequency electromagnetic field characteristic to each of the at least two electronically controllable electromagnetic unit cells; and 
 transmit the control signal to the at least two electronically controllable electromagnetic unit cells, the respective assigned radiofrequency electromagnetic field characteristics collectively causing the at least two electronically controllable electromagnetic unit cells to create the selected quasi-static electromagnetic field pattern within the electromagnetic cavity. 
   
     
     
         19 . The system of  claim 18 , wherein the electromagnetic structure is electrically insulated from the living vertebrate subject. 
     
     
         20 . The system of  claim 18 , wherein the electromagnetic structure includes at least one of an open electromagnetic cavity structure, a leaky open electromagnetic cavity structure, or a resonant open electromagnetic cavity structure. 
     
     
         21 . The system of  claim 18 , wherein a first portion of the surface includes the radiofrequency electromagnetic field source and a second portion of the surface includes a passive surface, the passive surface including at least one of a conductive material, a composite medium, an effective medium, a metamaterial, a metasurface, a semiconductor material, or an electromagnetically anisotropic surface. 
     
     
         22 . The system of  claim 18 , wherein the radiofrequency electromagnetic field source is configured to generate a near-field region electromagnetic field in at least a portion of the 1 Megahertz (MHz)-1 Gigahertz (GHz) range. 
     
     
         23 . The system of  claim 18 , wherein each artificially structured electromagnetic unit cell of the at least two artificially structured electromagnetic unit cells includes a respective controller configured to regulate electromagnetic fields generated by the respective electromagnetic unit cell in response to the control signal, wherein the controller is configured to regulate a phase, polarization, wave impedance, or amplitude of electromagnetic fields generated by the respective electromagnetic unit cell. 
     
     
         24 . The system of  claim 18 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern responsive to (i) a parameter of the subwavelength electromagnetic cavity, and (ii) a parameter of the perturbing object. 
     
     
         25 . The system of  claim 18 , wherein the selector circuit is configured to select the quasi-static electromagnetic field pattern in response to a model-based estimation of an electric field power density localized to the volume adjoining the exterior surface of the perturbing object. 
     
     
         26 . A method comprising:
 selecting a quasi-static electromagnetic field pattern creating a radiofrequency electric field in a subwavelength electromagnetic cavity, the subwavelength electromagnetic cavity defined at least in part by a surface of an electromagnetic structure and an exterior surface of a perturbing object implanted within or proximate to a subject;   assigning a respective radiofrequency electromagnetic field characteristic to each of at least two electronically controllable, artificially structured electromagnetic unit cells of a radiofrequency electromagnetic field source associated with the surface of the electromagnetic structure, the respective assigned radiofrequency electromagnetic field characteristics collectively creating the selected quasi-static electromagnetic field pattern within the electromagnetic cavity;   implementing the assigned respective radiofrequency electromagnetic field characteristic in each of the at least two electronically controllable, artificially structured electromagnetic unit cells; and   creating the selected quasi-static electromagnetic field pattern.   
     
     
         27 . The method of  claim 26 , wherein the electromagnetic structure includes an electromagnetic cavity structure. 
     
     
         28 . The method of  claim 26 , comprising electrically insulating the electromagnetic structure from the living vertebrate subject. 
     
     
         29 . The method of  claim 26 , wherein the electromagnetic structure supports at least two quasistatic radiofrequency electromagnetic field patterns, where the at least two quasi-static radiofrequency electromagnetic field patterns are resonant modes or eigenmodes of the electromagnetic cavity structure. 
     
     
         30 . The method of  claim 26 , wherein the radiofrequency electromagnetic field source is configured to generate a near-field region electromagnetic field in at least a portion of the 1 Megahertz (MHz)-1 Gigahertz (GHz) range. 
     
     
         31 . The method of  claim 26 , comprising randomly accessing each artificially structured electromagnetic unit cell. 
     
     
         32 . The method of  claim 26 , wherein each artificially structured electromagnetic unit cell of the at least two artificially structured electromagnetic unit cells includes a respective controller, the method comprising regulating, by the controller a phase, polarization, wave impedance, or amplitude of electromagnetic fields generated by the respective electromagnetic unit cell. 
     
     
         33 . The method of  claim 26 , comprising selecting, by the selector circuit, the quasi-static electromagnetic field pattern responsive to real-time data received from a radiofrequency electromagnetic field sensor. 
     
     
         34 . The method of  claim 26 , comprising selecting, by the selector circuit, the quasi-static electromagnetic field pattern responsive to (i) a parameter of the subwavelength electromagnetic cavity, and (ii) a parameter of the perturbing object. 
     
     
         35 . The method of  claim 26 , comprising selecting, by the selector circuit, the quasi-static electromagnetic field pattern in response to indicia of a core temperature of the living vertebrate subject.