Apparatus and method for staged treatment of tissue

Abstract

Disclosed herein is a tissue treatment device and method including a plurality of spaced apart elongate electrodes configured to receive a radio frequency (RF) signal from a source of RF energy and to insert tissue at a plurality of depths. The elongated electrode has a first polarity and the single flat electrode has a second polarity. A single flat electrode is located proximate to the elongate electrode and is configured for contacting a tissue surface and for receiving an RF signal from an RF energy source. An actuation mechanism is connected to the plurality of elongate electrodes and is configured to move the elongate electrodes into and out of the tissue in two opposite directions. A controller, which is part of the treatment device, is configured to apply a staged treatment to tissue, change a spatial density of the staged treatment over a treatment time period, operate an actuation mechanism to selectively move different elongate electrode subsets of the plurality of elongate electrodes according to a treatment time pattern.

Description

[0001] Related applications

[0002] This application relates to and claims priority to U.S. Provisional Application No. 63 / 471,294, entitled “DEVICES AND METHODS FOR FRACTIONALTREATMENT OF TISSUE”, filed on June 6, 2023. Technical Field

[0003] This invention belongs to the field of medical aesthetics, and specifically relates to apparatus and methods for treating tissues (such as skin) for aesthetic and / or cosmetic purposes. More specifically, the disclosure relates to devices for grading and treating a patient's skin tissue. Background Technology

[0004] Various skin treatment techniques exist to revitalize the skin. Some treatments involve graded skin treatments, a term used to describe a form of treatment that creates a discrete array of relatively small treatment sites within the skin tissue, leaving areas of healthy, untreated tissue surrounding the treatment sites. Treatment sites can be created using optical (e.g., laser), electromagnetic (e.g., radio frequency), acoustic (e.g., ultrasound), or other energy / modal methods. At each treatment site, micro-damage is created within the skin tissue. This micro-damage at the treatment site initiates the skin tissue's natural healing response. The intact, healthy tissue surrounding the treatment site provides the foundation for healing the micro-damage.

[0005] Examples of graded skin treatments can be found in WO2021234609A1 and WO2021234605A1, both of which have been assigned to the assignee of this invention. Summary of the Invention

[0006] The subject matter of this invention provides a technique for grading tissues using microelectrodes to deliver electrical current (particularly alternating current (AC) signals). This invention provides devices and methods for effective grading by increasing treatment comfort and outcomes. Microelectrodes can be configured to have an elongated shape, enabling them to be inserted deep into tissues and optionally into layers of fat and / or muscle beneath the skin. For this purpose, hereinafter, microelectrodes have a length dimension much larger than their width and depth dimensions, and may be referred to as microneedles to describe their deep tissue insertion functionality.

[0007] According to a first aspect of the subject matter disclosed in this invention, a tissue processing apparatus is provided, comprising: a plurality of spaced-apart elongated electrodes configured to receive an RF signal of a first polarity from a radio frequency (RF) energy source and to be inserted into tissue at one or more depths; a single flat electrode located in proximity to the elongated electrodes and configured to receive an RF signal of a second polarity opposite to the first polarity from the RF energy source and to contact a tissue surface; an actuation mechanism connected to the plurality of elongated electrodes and configured to move the plurality of elongated electrodes into and out of tissue along a first axis in two opposite directions; and a controller connected to the plurality of elongated electrodes, the flat electrode, the RF energy source, and the actuation mechanism, the controller being configured to apply RF energy to the tissue and to actuate the actuation mechanism to insert and remove different RF needle groups of the plurality of spaced-apart elongated electrodes into and out of the tissue, thereby selectively and variably providing graded processing to the tissue.

[0008] In another aspect, a tissue processing apparatus includes a controller configured to operate an RF energy source during an insertion phase and a subsequent processing phase. The insertion phase comprises applying RF signals to a plurality of elongated electrodes to induce ablation of tissue in distal contact with the elongated electrodes. The controller is further configured to vary the spatial density of the graded processing during a processing time period by operating an actuation mechanism to selectively move different subgroups of the plurality of elongated electrodes according to a processing time pattern. The spatial density is equal to or equal to 1 / 100000 of a first distance. The second distance varies between them.

[0009] In another aspect, a tissue processing apparatus includes a first distance equal to 2.2 mm, and a plurality of elongated electrodes comprising a first elongated electrode array spaced apart by a first distance and a second elongated electrode array spaced apart by a second distance, the first array and the second array defining different elongated electrode subgroups. In another tissue processing apparatus, the first distance and the second distance are equal and 2.2 mm, and the first array includes a first number of elongated electrodes extending along a second axis, and the second array includes a second number of elongated electrodes extending along the second axis, the second number being less than the first number.

[0010] In another aspect, there exists a tissue processing apparatus in which, when each elongated electrode of the second array is inserted into tissue, each elongated electrode is equidistantly positioned from every four adjacent elongated electrodes of the first array, and an actuation mechanism includes a first actuation motor connected to the first array and a second actuation motor connected to the second array, the first and second actuation motors being independently controllable by a controller. Furthermore, in another tissue processing apparatus, the elongated electrodes of the first array have equal first lengths, and the elongated electrodes of the second array have equal second lengths, and the first elongated electrode array is positioned above a first stand, and the second elongated electrode array is positioned above a second stand, the first and second stands being movable relative to each other along a first axis by an actuation mechanism.

[0011] In one aspect, there is a tissue processing apparatus in which a second stand is arranged behind a first stand along a first axis, the first stand including holes along the first axis through which a second elongated electrode array can pass, and a plurality of elongated electrodes having different lengths. The tissue processing apparatus further includes one or more depths comprising a maximum depth between 7 mm and 10 mm, and at least some of the elongated electrodes having flat bodies. The tissue processing apparatus further includes a flat body of each electrode in the first array having a length of 3 mm, a width and thickness of 100 μm to 200 μm, and a flat body of each electrode in the second array having a length of 7 mm, a width and thickness of 200 μm to 300 μm.

[0012] In another aspect, there is a tissue processing device in which at least some of a plurality of elongated electrodes have at least one of the following: a curved body; a blunt distal end; a pointed distal end; different cross-sectional shapes; different cross-sectional areas; insulation along its proximal outer surface; or insulation along its entire outer surface except its bottom side.

[0013] In one aspect, there is a tissue processing device in which at least some of a plurality of elongated electrodes are arranged in a plurality of comb-shaped one-dimensional arrays, and flat electrodes are perforated, with the plurality of elongated electrodes passing through these holes along a first axis. The tissue processing device further includes: a body configured to be held by a user, the body housing an actuation mechanism and a controller; and a disposable end removably connected to the body and housing the plurality of elongated and flat electrodes. The tissue processing device also includes an RF energy source housed within the body.

[0014] In another aspect, a tissue processing device, wherein the controller is further configured to change the spatial density by means of an actuation mechanism that: a) during an insertion phase, operates an RF energy source with a first RF signal profile that causes ablation of tissue contacting the distal ends of the plurality of elongated electrodes, and operates the actuation mechanism to move the plurality of elongated electrodes into the tissue; b) during a processing phase, operates the RF energy source with a second RF signal profile that causes graded processing of tissue contacting the distal ends of the plurality of elongated electrodes for a predetermined processing time period; and c) during a disengagement phase, operates the actuation mechanism to move the plurality of elongated electrodes out of the tissue.

[0015] In one aspect, a tissue processing apparatus, wherein a controller is further configured to sequentially repeat operations (a) and (b) two or more times corresponding to different subgroups of a plurality of elongated electrodes, thereby changing the spatial density of the processing. The tissue processing apparatus further includes a controller configured to operate an RF energy source with a third RF signal profile during a disengagement phase.

[0016] On the other hand, there is a method for classifying tissues, which includes:

[0017] supply:

[0018] Multiple slender electrodes, each having a first polarity; and

[0019] A single flat electrode is located near an elongated electrode and has a second polarity opposite to the first polarity;

[0020] place:

[0021] A single flat electrode contacts the tissue surface; and

[0022] The ends of multiple slender electrodes are in contact with the tissue surface;

[0023] Provide a first RF signal profile to the elongated electrode and the single flat electrode;

[0024] When a closed circuit is detected between multiple elongated electrodes and a single flat electrode, a second RF signal profile is provided that is suitable for inducing ablation of tissue in contact with the ends of the multiple elongated electrodes.

[0025] When the second RF signal is provided, different groups of RF needles with multiple elongated electrodes are selectively and variably inserted into the tissue at a predetermined rate corresponding to tissue ablation within a predetermined time period, until a predetermined depth is reached; and

[0026] Multiple thin electrodes were withdrawn from the tissue.

[0027] In one aspect, the method further includes the steps of repeatedly providing a first RF signal and a second RF signal, and inserting the plurality of elongated electrodes, before withdrawing the plurality of elongated electrodes. The method further includes providing a third RF signal profile configured to process the tissue at the predetermined depth for a predetermined processing time period after the plurality of elongated electrodes have reached a predetermined depth and before withdrawing the plurality of elongated electrodes from the tissue. The method further includes measuring the impedance of the tissue and determining the second RF signal profile based on the measured impedance. The method further includes measuring the impedance of the tissue and determining the third RF signal profile based on the measured impedance. Attached Figure Description

[0028] To better understand the subject matter disclosed herein and to illustrate how it can be implemented in practice, implementation methods will now be described by way of non-limiting example only with reference to the accompanying drawings.

[0029] Figures 1A to 1C A non-limiting exemplary embodiment of the device according to the present invention is shown.

[0030] Figure 2 A non-limiting exemplary embodiment of the method according to the present invention is shown.

[0031] Figures 3A to 3G Another non-limiting exemplary embodiment of a device having two needle electrode arrays according to the present invention is shown.

[0032] Figures 4A to 4F Various shapes of elongated (needle) electrodes for use in devices according to a non-limiting embodiment of the invention are shown. Detailed Implementation

[0033] The use of elongated electrodes (microneedles) for grading can be limited by various factors, such as the mechanical properties of the thin and elongated shape of the microneedles: the size and strength of the needles limit the spatial density and depth of the treatment. In some implementations, needles are inserted by heating and ablation rather than mechanical insertion force, and effective treatment (comfort and results) is achieved by varying the spatial density of the grading treatment over the treatment period.

[0034] For a given thermal relaxation time (TRT) of tissue, the ability to achieve higher spatial density tiered treatment than typical conventional microneedles can be achieved by using tiered treatment with lower energy (per electrode / needle) and / or higher temporal resolution than typical conventional microneedles. In some embodiments, multi-pulse schemes avoid bulk heating and treat specific conditions more effectively. In some embodiments, more efficient heating leads to the desired results without over-treating / burning the treated tissue.

[0035] An AC signal can be applied to tissue via microelectrodes; this can be an RF signal, meaning the signal frequency is in the RF region of the electromagnetic spectrum. However, this should not limit the invention, as other regions of the electromagnetic spectrum can also be applicable.

[0036] refer to Figures 1A to 1C The diagram illustrates, in block form, a non-limiting example of a device 100 for grading tissue 10 (as used herein, tissue specifically includes skin and may include additional tissues such as fat or muscle) according to some non-limiting embodiments of the subject matter disclosed in this invention. As shown, device 100 includes a plurality of spaced-apart microelectrodes (microneedle electrodes) 110, a single flat electrode 120, an actuation mechanism 130, and a controller 140. As mentioned above, the specific non-limiting examples mentioned herein may be referred to as radio frequency (RF) electrodes.

[0037] Multiple spaced-apart RF needle electrodes 110 are configured to receive RF energy (signals) from an RF (AC) source 150 and for insertion into skin tissue to one or more depths. It should be noted that although the electrical signal illustrated herein is AC, it could also be DC (direct current) or a combination thereof. Figure 1A As can be understood, the RF power source 150 is not part of the device 100, but in some embodiments, it may be part of the device 100A, which includes both the device 100 and the RF source 150, such as... Figure 1A As shown by the dashed lines. In some embodiments, the plurality of RF needle electrodes are arranged to form a one-dimensional array. In some embodiments, the plurality of RF needle electrodes are arranged to form a two-dimensional array. In some embodiments, the plurality of RF needle electrodes have equal lengths. In some embodiments, the plurality of RF needle electrodes have different lengths. In some embodiments, the plurality of RF needle electrodes are spaced apart at a fixed, equal distance between every two adjacent needles. In some embodiments, the plurality of RF needle electrodes are spaced apart at varying, unequal distances between at least some of the needles.

[0038] A single flat RF electrode 120 is configured to contact the surface 12 of skin tissue 10 and to receive RF energy from an RF energy source. A plurality of RF needle electrodes 110 are configured to be connected to a first pole of the RF energy source, thus having a first polarity, and the flat RF electrode 120 is configured to be connected to the opposite second pole of the RF energy source, thus having a second polarity opposite to the first polarity of the plurality of RF needle electrodes 110. It should be understood that at any given time, the first polarity of the RF needle electrode 110 will be opposite to the second polarity of the flat RF electrode 120, although the first and second polarities can be switched back and forth according to the frequency of the RF signal provided by the RF signal source 150.

[0039] Generally, the two electrodes are arranged to operate in either a unipolar or bipolar activation mode. This is influenced by two main factors: current density and physical distance. Typically, in unipolar mode, the first and second electrodes produce different current densities (higher versus lower) while being far apart from each other (e.g., a smaller first electrode (higher current density) is located at the finger of the object, and a larger second electrode (lower current density) is located at the lower back of the object). Typically, in bipolar mode, the first and second electrodes produce similar (specifically, equal) current densities while being close to each other.

[0040] In some implementations, the plurality of elongated RF electrodes 110 and the single flat RF electrode 120 operate in a pseudo-mono-bipolar (or duo-polar) mode because each of the plurality of elongated electrodes 110 generates a higher current density than the single flat RF electrode 120 (as in unipolar mode), while the plurality of elongated electrodes 110 and the single flat electrode 120 are close to each other.

[0041] Therefore, the device 100 can operate in a bipolar mode, such that each of the plurality of RF needle electrodes operates against a single flat RF electrode 120. Since the surface area of ​​the single flat RF electrode 120 is much larger than the surface area of ​​the tip 110T of each RF needle electrode, the RF current density at the needle tip is sufficiently high, resulting in very high temperatures in the tissue near the needle tip, and these very high temperatures cause tissue ablation, as indicated by the tissue pores 10H around the insertion portion of the RF needle electrode. Thus, the device 100 is configured to insert multiple RF needle electrodes into tissue by heating and ablation of the tissue without excessive insertion force.

[0042] In some embodiments, multiple RF needle electrodes and a single flat RF electrode should be close to each other to achieve a bipolar mode. In some embodiments, the RF needle electrodes and the flat RF electrode are located next to each other relative to the skin surface. In some embodiments, the RF needle electrodes and the flat RF electrode intersect each other relative to the skin surface; for example, the single flat RF electrode includes holes through which multiple RF needle electrodes pass.

[0043] An actuation mechanism 130 is connected to a plurality of RF needle electrodes 110 and is configured and operable to move the plurality of RF needle electrodes into and out of skin tissue 10 in two opposite directions along a first axis. In some embodiments, the first axis is perpendicular to the skin surface 12. It should be understood that the actuation mechanism can be configured and controlled to move the RF needle electrodes individually or in a predefined group according to a treatment protocol. In some embodiments, the actuation mechanism is configured to insert the plurality of RF needles into the skin tissue and / or deeper into fat and / or muscle tissue to one or more depths. In some embodiments, the maximum depth is determined by the length of at least some of the plurality of RF needle electrodes. In some embodiments, the maximum depth is approximately 7 mm.

[0044] The controller 140 is operatively connected to a plurality of RF needle electrodes, flat electrodes, an RF energy source, and an actuator for controlling graded RF treatment of skin tissue (and / or fat and / or muscle tissue) and applying graded RF treatment to skin tissue (and / or fat and / or muscle tissue). The controller is specifically configured to control RF energy parameters, such as the frequency and amplitude of the RF signal, processing time, duty cycle, selection of the activated RF needle electrode, and to control the actuator responsible for advancing and retracting the activated RF needle electrode toward and away from the skin tissue.

[0045] The controller 140 can be configured to operate the RF energy source 150 during the insertion and subsequent treatment phases. The insertion phase includes applying RF energy to a plurality of RF needle electrodes and a flat electrode to induce ablation of skin tissue near the distal ends of the RF needle electrodes. Furthermore, the controller 140 can be configured to vary the spatial density of the graded RF treatment during the treatment period by operating the actuator 130 to selectively move different RF needle subgroups of the plurality of RF needle electrodes according to a treatment time pattern.

[0046] exist Figure 1B and Figure 1C The diagram illustrates a non-limiting example of changing the spatial density of hierarchical RF processing via controller 140. In the example, the user can decide that the multiple RF needle electrodes 110 should be divided into three subgroups: subgroup 110A, which includes three RF needle electrodes; subgroup 110B, which includes one RF needle electrode; and subgroup 110C, which includes one RF needle electrode.

[0047] In the first time period t1, the controller 140 operates the RF power source 150 and the actuation mechanism 130 to insert subgroup 110A to depth D1 and apply a grading process with a spatial density SD1. For simplicity, it is assumed that the five RF needle electrodes 110 are placed adjacent to each other in a row, with a distance of X between every two adjacent needle electrodes. Therefore, the spatial density SD1 corresponds to a distance of 2X between every two adjacent needle electrodes of subgroup 110A. In the second time period t2, the controller 140 may operate the RF power source 150 and the actuation mechanism 130 to insert subgroup 110B to depth D2 and apply a grading process using subgroups 110A and 110B. It should now be understood that the grading RF process has a spatial density SD1 between the two RF needle electrodes on the left side of subgroup 110A and a spatial density SD2 between the three RF needle electrodes on the right side (two of subgroup 110A and one of subgroup 110B).

[0048] Therefore, the spatial density of hierarchical RF processing can vary over the processing time period. It should be understood that, in the non-limiting example, spatial density SD2 is twice the spatial density SD1. It should also be understood that depths D1 and D2 can be equal or different.

[0049] In a non-limiting example, although subgroup 110C is not activated, it should be understood that it can be controlled by controller 140 and inserted into depth D3 (not shown, equal to or different from D1, D2) such that the graded RF treatment begins at spatial density SD1 and continues at spatial density SD2 over the entire treated skin tissue portion, and vice versa.

[0050] Although not specifically shown, it is conceivable that during time period t3, one or more subgroups of subgroups 110A to 110C may be withdrawn / retracted from the skin tissue to change the spatial density of the treatment again or to terminate the treatment.

[0051] It should also be noted that different subgroups can be inserted and withdrawn sequentially during session processing. For example, a multi-step approach can be implemented, first inserting and withdrawing subgroup 110A / B / C, and then inserting and withdrawing other subgroups 110B / C / A.

[0052] In some embodiments, the apparatus includes an impedance measurement device / circuit 160 configured to measure the impedance of tissue during a process that includes inserting and withdrawing an RF needle electrode 110 into and from the tissue, and applying the treatment at one or more predetermined depths. The impedance measurement results are transmitted to a controller 140, which accordingly controls RF signals to enable the insertion of the RF needle electrode and the implementation of the treatment.

[0053] In some implementations, the impedance of the tissue is estimated based on the depth of penetration into the tissue. For example, controller 140 may use a lookup table of impedance values ​​as a function of depth to adapt the RF signal to a specific depth. In some implementations, the impedance of the tissue is estimated based on the tissue type. In some implementations, the impedance is estimated based on a combination of depth and tissue type.

[0054] refer to Figure 2 The flowchart illustrates an example of a method 10 for applying a grading treatment to skin tissue according to some non-limiting embodiments based on the published text.

[0055] In step 10a, a plurality of elongated RF (needle) electrodes having a first polarity are provided.

[0056] In step 10b, a single flat RF electrode with a second polarity opposite to the first polarity is provided.

[0057] In step 10c, a single flat electrode is positioned to make contact with the surface of the skin tissue.

[0058] In step 10d, the ends of one or more subgroups of the plurality of RF needle electrodes are brought into contact with the skin tissue surface.

[0059] In step 10e, a first RF signal is provided to the RF needle electrode and a single flat RF electrode to confirm contact between the tip of the needle electrode and the flat electrode and the tissue.

[0060] In step 10f, once a closed circuit is detected in step 10e, a second RF signal is provided, configured to cause ablation of skin tissue in contact with the ends of one or more subgroups. In some embodiments, the second RF signal may have a value in the range of 10W to 100W.

[0061] In step 10g, while the second RF signal is provided, one or more subgroups are advanced / inserted into the skin tissue at a predetermined rate (speed) corresponding to the ablation of the skin tissue within a predetermined insertion time period until a predetermined depth is reached. It is understood that the second RF signal can be adjusted to apply treatment simultaneously with the insertion or withdrawal of the needle electrode.

[0062] In step 10h, during any of steps 10e to 10g, the controller uses sensors to measure the tissue impedance continuously or discretely, and adjusts / adapts the parameters of the second RF signal accordingly to achieve ablation and insertion of the needle RF electrodes and tissue treatment. In some embodiments, other factors are considered when adjusting / adapting the value / parameters of the second RF signal, such as depth, energy density (number of working needle electrodes), insertion speed, and tissue type. For example, it is known that the outer layer of skin tissue (stratum corneum) has a higher impedance than deeper layers of skin tissue; therefore, when ablating the stratum corneum, a second RF signal with a higher power profile is required compared to the power profile required for ablating deeper tissue.

[0063] Therefore, it can be understood that the second RF signal can have a varying profile and be divided into penetrating pulses (pulses capable of ablating the stratum corneum) and working pulses (pulses capable of ablating deeper tissue layers), with the working pulses having a smaller magnitude than the penetrating pulses.

[0064] In step 10i, optionally, a third RF signal configured to treat skin tissue with heat is provided at a predetermined depth for a predetermined treatment time period. In some embodiments, the value / parameter of the third RF signal is determined based on impedance, depth, treatment time period, and energy density (number of working needle electrodes).

[0065] It should be understood that steps 10g to 10i can be repeated sequentially several times to apply graded treatment to different depths within the skin tissue.

[0066] Optionally, in step 10j, steps 10e to 10i are repeated using one or more subgroups of a plurality of RF needle electrodes to apply graded RF treatment with varying spatial density to the skin tissue.

[0067] In step 10k, the subgroups of multiple RF needle electrodes that have been (through ablation) inserted into the skin tissue are withdrawn from the skin tissue, and the treatment is completed. It is understood that a second and / or third RF signal may also be applied during the withdrawal of the needle electrodes. It is also understood that, for illustration and understanding, the division of the first, second, and third RF signals described above is presented, and alternatively, a combined single adaptive RF signal may exist, adjusted through different stages of contact detection, ablation insertion, treatment, and withdrawal of the needle electrodes.

[0068] It should be understood that method 10 can be applied using the device described with reference to Figure 1.

[0069] refer to Figure 3A This illustrates a non-limiting example of a device 200 configured according to the publicly available text. The number with a difference of one hundred is used to refer to a device having... Figures 1A to 1CThe device 200 has the same / similar functional elements / features as described above. The device 200 has a housing / encapsulation 202 configured to encapsulate a plurality of RF needle electrodes, a single flat electrode, an actuation mechanism, and a controller. Optionally, the housing 202 may also encapsulate an RF power source therein. As shown in a non-limiting example, the housing 202 has a gun-like form and includes a handle 204 configured to be gripped by a user of the device.

[0070] like Figure 3B As shown, in some embodiments, the device housing includes a body 200A, and the body includes a handle 204. For example... Figure 3G As shown, the body 202A houses the actuation mechanism 230 and the controller 240; in this example, the controller is located within the handle 204. The housing also includes a disposable end 202B, which is removably connected to the body 202A and houses multiple RF pin electrodes and flat RF electrodes, as will be further described below. In some embodiments, a connector 202C for transmitting signals (including RF signals) between the actuation mechanism and the controller to the multiple RF pin electrodes and flat RF electrodes is located at the interface between the body and the disposable end. In one example, as shown, the connector 202C is in the form of a pogo pin.

[0071] exist Figure 3C The exploded view of the disposable end 202B with internal parts is shown in the figure, and... Figure 3G The image shows a side cross-sectional view of the assembled disposable end. A single flat electrode 220 is located at the distal end configured to touch and contact skin tissue. The flat electrode 220 is perforated and has multiple holes corresponding to multiple RF needle electrodes, such that the RF needle electrodes pass through these holes toward the skin tissue.

[0072] The plurality of RF needle electrodes 210 include two needle electrode subgroups: a first two-dimensional needle array 210A and a second two-dimensional needle array 210B, which are arranged in series with respect to the axis X. The first array 210A is received within a guide 206, and the second array 210A is received within a guide 208. The guides 206 and 208 are connected to an actuation mechanism so that each guide and the corresponding needle array can move back and forth along the axis X.

[0073] In some embodiments, the first array includes a first number of RF needle electrodes extending along a plane orthogonal to the X-axis, and the second array includes a second number of RF needle electrodes extending along the plane. In some embodiments, the second number is less than the first number.

[0074] In some embodiments, the RF needle electrodes of the first array are spaced apart by a first distance, and the RF needle electrodes of the second array are spaced apart by a second distance. In some embodiments, the first distance and the second distance determine the spatial density of the hierarchical treatment sites. In some embodiments, the first distance and the second distance are equal. In some embodiments, the RF needle electrodes of the first array have equal first lengths, and the RF needle electrodes of the second array have equal second lengths.

[0075] In a non-limiting example, the first array 210A includes 6x6 RF pins arranged at equal intervals therebetween, and the second array 210B includes 5x5 RF pins arranged at equal intervals therebetween, such that each RF pin of the second array is equidistant from every four RF pins of the first array. Thus, if the distance between two adjacent RF pins in the first array is *a*, then the distance between every two adjacent RF pins in the second array is also *a*, and the distance between each RF pin of the first array and its adjacent RF pins in the second array is *a* / *a*. Therefore, if the distance between adjacent needles in each array is 2.2 mm, the spatial density of RF treatment sites will be 2.2 mm when only one of the first and second arrays is inserted into the skin tissue, and 2.2 mm when both arrays are inserted. Variations between mm.

[0076] As shown in the figure, in some embodiments, a first array 210A is positioned above a first mount 210AA, and a second array 210B is positioned above a second mount 210BB. The first and second mounts are movable relative to each other along axis X by an actuation mechanism 230. The first and second mounts can also serve as PCBs to electrically connect RF pin electrodes to a controller 240 and an RF power source. As shown in the example, the second mount 210BB is arranged behind the first mount 210AA along axis X, and the first mount 210AA has a hole along axis X to allow the second array 210B to pass through.

[0077] In some embodiments, such as the example in FIG3H, the actuation mechanism 230 includes a first actuation motor 230A connected to a first array 110A and a second actuation motor 230B connected to a second array 110B. In some embodiments, the first and second actuation motors can be independently controlled by a controller 240 to independently move the first and second arrays in two directions along axis X. The first and second actuation motors can be linear motors and can have a continuous movement mechanism or a stepping movement mechanism.

[0078] Figure 3D and Figure 3ENon-limiting embodiments of RF needle electrodes that can be used with devices disclosed herein are shown. In some embodiments, some or all of these RF needle electrodes have a flat body rather than a circular shape, having both width and thickness. In some embodiments, the flat body has a width different from its thickness. In some embodiments, the width and thickness are equal, for example, in the range of 150 μm to 250 μm. It should be understood that the longer the needle, the thicker it can be made to withstand the forces acting upon it.

[0079] In some embodiments, at least some of these RF needle electrodes have different cross-sectional shapes (e.g., circular, rectangular, polygonal). In some embodiments, at least some of the RF needle electrodes having the same cross-sectional shape have different cross-sectional areas (e.g., a first group / array of needle electrodes has a circular shape with a first cross-sectional area, and a second group / array of needle electrodes has a circular shape with a second cross-sectional area different from the first cross-sectional area).

[0080] As described above, by ablating the inserted RF needle electrodes, these needles do not need to have a sharp distal end for puncturing tissue. In some embodiments, some or all of these RF needle electrodes have a blunt distal end. In some embodiments, some or all of these RF needle electrodes have a distal end that is not necessarily sharp. In some embodiments, some or all of these RF needle electrodes are insulated along their proximal outer portion, leaving only the distal end conductive when in contact with surrounding tissue. In some embodiments, some or all of these RF needle electrodes are insulated along their entire length (outer surface), except that only the bottom side (face) is conductive. The bottom surface may be flat or may be curved. Among other things, complete insulation ensures that ablation proceeds along the advancing movement and enables focused and controlled localized graded RF treatment at the selected depth.

[0081] In the example shown, a first array 110A is shown, which has 6x6 needles that are insulated along the entire proximal length 210P of the needles except for the distal end 210DE with exposed conductive material.

[0082] In some implementations, the RF needle electrodes are arranged in a plurality of comb-shaped one-dimensional arrays. This enhances the needle strength and facilitates its fabrication. As shown in this example, the first array 210A includes six comb-shaped needle arrays 2101 to 2106, which are arranged next to each other to form a 6x6 two-dimensional array.

[0083] refer to Figures 4A to 4F This illustrates a non-limiting example of an elongated microelectrode configured according to the present invention.

[0084] Figures 4A to 4B This is a side view showing the insulation on the outer surface of the needle electrode. Figure 4A A preferred insulating profile 412A is shown, which extends the entire length L of the elongated needle electrode 410A. The conductive portion 414A is located on the bottom side of the needle electrode. Figure 4B Another insulating profile 412B is shown, which extends for most of the length of the elongated needle electrode 410B. The conductive portion 414B extends along a portion of the length of the needle electrode and the bottom side.

[0085] Figure 4C The diagram shows a circular (or elliptical) cross-section of the needle electrode perpendicular to its length.

[0086] Figure 4D A rectangular cross-section of the needle electrode perpendicular to its length is shown.

[0087] Figure 4E A preferred flat tip 410T1 (with a circular or rectangular outer shape) is shown, which can mate with either needle electrode 410A or 410B. As mentioned above, the tip can be flat because mechanical puncture is not required.

[0088] Figure 4F The pyramidal or conical ends are shown, which can be used with needle electrodes 412A and 412B respectively.

[0089] It should be noted and understood that other insulating shapes, cross-sections, and ends are also possible within the scope of this invention. Therefore, by utilizing subgroups of needle electrodes for controlled insertion and withdrawal from tissue, the subject matter disclosed in this invention achieves graded treatment with variable spatial density. This results in less painful and more intensive treatment, leading to better outcomes.

Claims

1. A tissue treatment apparatus comprising: a plurality of spaced-apart elongate electrodes configured to: receive, from a radio frequency (RF) energy source, an RF signal at a first polarity; and insert into tissue at one or more depths; a single flat electrode located proximate to the elongate electrodes and configured to contact a tissue surface and receive, from the RF energy source, the RF signal at a second polarity opposite the first polarity; an actuation mechanism connected to the plurality of elongate electrodes and configured to move the plurality of elongate electrodes in and out of the tissue along a first axis in two opposite directions; and a controller connected to the plurality of elongate electrodes, the flat electrode, the RF energy source, and the actuation mechanism, the controller configured to: apply RF energy to the tissue; and actuate the actuation mechanism to insert and remove different subgroups of RF needles of the plurality of spaced-apart elongate electrodes into and out of the tissue to selectively and variably provide a graduated treatment to the tissue.

2. The tissue treatment apparatus of claim 1, wherein the controller is configured to operate the RF energy source in an insertion phase and a subsequent treatment phase, the insertion phase including applying the RF signal to the plurality of elongate electrodes to cause ablation of the tissue in contact with distal ends of the elongate electrodes.

3. The tissue treatment apparatus of claim 1, wherein the controller is further configured to vary a spatial density of the graduated treatment over a treatment time period by operating the actuation mechanism to selectively move different subgroups of elongate electrodes of the plurality of elongate electrodes according to a treatment time pattern.

5. The tissue treatment apparatus of claim 4, wherein the first distance is equal to 2.2 mm.

6. The tissue treatment apparatus of claim 1, wherein the plurality of elongate electrodes includes a first array of elongate electrodes spaced apart by a first distance and a second array of elongate electrodes spaced apart by a second distance, the first and second arrays defining the different subgroups of elongate electrodes.

7. The tissue treatment apparatus of claim 6, wherein the first distance and the second distance are equal.

4. The tissue treatment device of claim 3, wherein the spatial density varies between a first distance and a second distance equal to 1 / 2 of the first distance.

4. The tissue treatment device of claim 3, wherein the spatial density varies between a first distance and a second distance equal to 1 / 2 of the first distance.

4. The tissue treatment device of claim 8. The tissue treatment apparatus of claim 7, wherein the first distance and the second distance are equal to 2.2 mm.

9. The tissue treatment apparatus of claim 6, wherein the first array includes a first number of elongate electrodes extending along a second axis and the second array includes a second number of elongate electrodes extending along the second axis, the second number being less than the first number.

10. The tissue treatment apparatus of claim 6, wherein each elongate electrode of the second array is positioned equidistant from every fourth adjacent elongate electrode of the first array when inserted into the tissue.

11. The tissue treatment apparatus of claim 6, wherein the actuation mechanism includes a first actuation motor connected to the first array and a second actuation motor connected to the second array, the first and second actuation motors being independently controllable by the controller. ​ ​ ​ 12. The tissue treatment device of claim 6, wherein the elongated electrodes of the first array have equal first lengths, and the elongated electrodes of the second array have equal second lengths.

13. The tissue treatment device of claim 6, wherein the first array of elongated electrodes is positioned above a first gantry, and the second array of elongated electrodes is positioned above a second gantry, the first and second gantries being movable relative to each other along the first axis by the actuation mechanism.

14. The tissue treatment device of claim 13, wherein the second gantry is disposed behind the first gantry along the first axis, the first gantry including a hole along the first axis that enables the second array of elongated electrodes to pass therethrough.

15. The tissue treatment device of claim 1, wherein the plurality of elongated electrodes have different lengths.

16. The tissue treatment device of claim 1, wherein the one or more depths include a maximum depth of between 7 mm and 10 mm.

17. The tissue treatment device of claim 1, wherein at least some of the plurality of elongated electrodes have a flattened body.

18. The tissue treatment device of claim 17, wherein the flattened body of each electrode in the first array has a length of 3 mm and respective widths and thicknesses of 100-200 pm.

19. The tissue treatment device of claim 17, wherein the flattened body of each electrode in the second array has a length of 7 mm and respective widths and thicknesses of 200-300 pm.

20. The tissue treatment device of claim 1, wherein at least some of the plurality of elongated electrodes have at least one of: a curved body; a blunt distal end; a sharp distal end; different cross-sectional shapes; different cross-sectional areas; insulation along a proximal outer surface thereof; or insulation along an entire outer surface thereof except a bottom side thereof.

21. The tissue treatment device of claim 1, wherein at least some of the plurality of elongated electrodes are arranged in a plurality of comb-like one-dimensional arrays.

22. The tissue treatment device of claim 1, wherein the flattened electrode is perforated, the plurality of elongated electrodes passing through the perforations along the first axis.

23. The tissue treatment device of claim 1, comprising: a body configured to be held by a user, the body housing the actuation mechanism and the controller; and a disposable tip removably connectable to the body and housing the plurality of elongated electrodes and the flattened electrode.

24. The tissue treatment device of claim 23, further comprising an RF energy source housed within the body.

25. The tissue treatment device of claim 3, wherein the controller is further configured to vary the spatial density by actuating the mechanism by: ​ a) operating the RF energy source during an insertion phase with a first RF signal profile to cause ablation of tissue contacting distal ends of the plurality of elongate electrodes, and operating the actuation mechanism to move the plurality of elongate electrodes into the tissue; b) operating the RF energy source during a treatment phase with a second RF signal profile to cause fractional treatment of tissue contacting the distal ends of the plurality of elongate electrodes for a predetermined treatment time period; and c) operating the actuation mechanism to move the plurality of elongate electrodes out of the tissue during a disengagement phase.

26. The tissue treatment device of claim 25, wherein the controller is further configured to repeat the (a) and (b) operations two or more times sequentially corresponding to different subsets of the plurality of elongate electrodes, thereby varying a spatial density of the treatment.

27. The tissue treatment device of claim 25, wherein the controller is configured to operate the RF energy source with a third RF signal profile during the disengagement phase.

28. A method for fractional treatment of tissue, the method comprising: providing: a plurality of elongate electrodes having a first polarity; and a single flat electrode located in proximity to the elongate electrodes and having a second polarity opposite the first polarity; placing: the single flat electrode in contact with a tissue surface; and ends of the plurality of elongate electrodes in contact with the tissue surface; providing a first RF signal profile to the elongate electrodes and the single flat electrode; upon detecting a closed circuit between the plurality of elongate electrodes and the single flat electrode, providing a second RF signal profile adapted to cause ablation of the tissue in contact with the ends of the plurality of elongate electrodes; simultaneously with providing the second RF signal, selectively and variably inserting different RF needle subsets of the plurality of elongate electrodes into the tissue at a predetermined rate corresponding to the ablation of the tissue for a predetermined time period until reaching a predetermined depth; and withdrawing the plurality of elongate electrodes out of the tissue. The steps of providing the first and second RF signals and inserting the plurality of elongate electrodes are repeated prior to withdrawing the plurality of elongate electrodes.

29. The method of claim 28, further comprising: After the plurality of elongate electrodes reach the predetermined depth and prior to withdrawing the plurality of elongate electrodes out of the tissue, a third RF signal profile configured to treat the tissue is provided at the predetermined depth for a predetermined treatment time period.

30. The method of claim 28, further comprising:

31. The method of claim 28, further comprising: measuring an impedance of the tissue; and determining the second RF signal profile based on the measured impedance.

32. The method of claim 31, further comprising: measuring an impedance of the tissue, and determining the third RF signal profile based on the measured impedance. ​

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