Electrosurgical Device Having a Multiplexer

[0001] 1. Technical Field

[0002] The present disclosure relates to the use of energy-based ablation instruments. More particularly, the present disclosure is directed to ablation device circuitry.

[0003] 2. Background of the Related Art

[0004] In the treatment of diseases such as cancer, certain types of cancer cells have been found to denature at elevated temperatures (which are slightly lower than temperatures normally injurious to healthy cells.) These types of treatments, known generally as hyperthermia therapy, typically utilize electromagnetic radiation to heat diseased cells to temperatures above 41° C., while maintaining adjacent healthy cells at lower temperatures where irreversible cell destruction will not occur. Other procedures utilizing electromagnetic radiation to heat tissue also include ablation and coagulation of the tissue. Such ablation procedures, e.g., such as those performed for menorrhagia, are typically done to ablate and coagulate the targeted tissue to denature or kill the tissue. Many procedures and types of devices utilizing electromagnetic radiation therapy are known in the art. Such therapy is typically used in the treatment of tissue and organs such as the prostate, heart, liver, lung, kidney, and breast.

[0005] One non-invasive procedure generally involves the treatment of tissue (e.g., a tumor) underlying the skin via the use of microwave energy. The microwave energy is able to non-invasively penetrate the skin to reach the underlying tissue. However, this non-invasive procedure may result in the unwanted heating of healthy tissue. Thus, the non-invasive use of microwave energy requires a great deal of control.

[0006] Presently, there are several types of microwave probes in use, e.g., monopole, dipole, and helical. One type is a monopole antenna probe, which consists of a single, elongated microwave conductor exposed at the end of the probe. A probe is typically surrounded by a dielectric sleeve. The second type of microwave probe commonly used is a dipole antenna, which consists of a coaxial construction having an inner conductor and an outer conductor with a dielectric junction separating a portion of the inner conductor. The inner conductor may be coupled to a portion corresponding to a first dipole radiating portion, and a portion of the outer conductor may be coupled to a second dipole radiating portion. The dipole radiating portions may be configured such that one radiating portion is located proximally of the dielectric junction, and the other portion is located distally of the dielectric junction. In the monopole and dipole antenna probe, microwave energy generally radiates perpendicularly from the axis of the conductor.

[0007] The typical microwave antenna has a long, thin inner conductor that extends along the axis of the probe and is surrounded by a dielectric material and is further surrounded by an outer conductor around the dielectric material such that the outer conductor also extends along the axis of the probe. In another variation of the probe that provides for effective outward radiation of energy or heating, a portion or portions of the outer conductor can be selectively removed. This type of construction is typically referred to as a “leaky waveguide” or “leaky coaxial” antenna. Another variation on the microwave probe involves having the tip formed in a uniform spiral pattern, such as a helix, to provide the necessary configuration for effective radiation. This variation can be used to direct energy in a particular direction, e.g., perpendicular to the axis, in a forward direction (i.e., towards the distal end of the antenna), or combinations thereof.

[0008] Invasive procedures and devices have been developed in which a microwave antenna probe may be either inserted directly into a point of treatment via a normal body orifice or percutaneously inserted. Such invasive procedures and devices potentially provide better temperature control of the tissue being treated. Because of the small difference between the temperature required for denaturing malignant cells and the temperature injurious to healthy cells, a known heating pattern and predictable temperature control is important so that heating is confined to the tissue to be treated. For instance, hyperthermia treatment at the threshold temperature of about 41.5° C. generally has little effect on most malignant growth of cells. However, at slightly elevated temperatures above the approximate range of 43° C. to 45° C., thermal damage to most types of normal cells is routinely observed. Accordingly, great care must be taken not to exceed these temperatures in healthy tissue.

[0009] In the case of tissue ablation, a high radio frequency electrical current in the range of about 500 mHz to about 10 gHz is applied to a targeted tissue site to create an ablation volume, which may have a particular size and shape. Ablation volume is correlated to antenna design, antenna performance, antenna impedance, and tissue impedance. The particular type of tissue ablation procedure may dictate a particular ablation volume in order to achieve a desired surgical outcome. By way of example, and without limitation, a spinal ablation procedure may call for a longer, narrower ablation volume, whereas in a prostate ablation procedure, a more spherical ablation volume may be required.

[0010] Systems and devices used for performing ablation procedures utilize sensors to determine if the system is working properly and to control the output of the microwave ablation device. Each sensor has a power line, ground line, and a data line that returns to the source of energy or generator. However, as ablation devices evolve the number of sensors will also increase. Thus, the number of power lines, ground lines, and data lines would also increase. Existing generators may only have a single power line, ground line and data line. As such, newer ablation systems and devices may not be configured for use with existing generators.

[0011] This description may use the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure. For the purposes of this description, a phrase in the form “A/B” means A or B. For the purposes of the description, a phrase in the form “A and/or B” means “(A), (B), or (A and B)”. For the purposes of this description, a phrase in the form “at least one of A, B, or C” means “(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C)”.

[0012] As shown in the drawings and as used in this description, and as is traditional when referring to relative positioning on an object, the term “proximal” refers to that portion of the apparatus, or component thereof, closer to the user and the term “distal” refers to that portion of the apparatus, or component thereof, farther from the user.

[0013] Electromagnetic energy is generally classified by increasing energy or decreasing wavelength into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. As it is used in this description, “microwave” generally refers to electromagnetic waves in the frequency range of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300 gigahertz (GHz) (3×10¹¹ cycles/second).

[0014] As it is used in this description, “ablation procedure” generally refers to any ablation procedure, such as, for example, microwave ablation, radiofrequency (RF) ablation, or microwave or RF ablation-assisted resection. As it is used in this description, “energy applicator” generally refers to any device that can be used to transfer energy from a power generating source, such as a microwave or RF electrosurgical generator, to tissue. For the purposes herein, the term “electrosurgical device” is interchangeable with the term “energy applicator”. As it is used in this description, “transmission line” generally refers to any transmission medium that can be used for the propagation of signals from one point to another. As used in this description, transmission line may be a power line, ground line, data line, signal line, or any other line configured to transmit data or energy.

[0015] As it is used in this description, “pressure sensor” generally refers to any pressure-sensing device capable of generating a signal representative of a pressure value. For the purposes herein, the term “pressure transducer” is interchangeable with the term “pressure sensor”.

[0016] Any of the herein described methods, programs, algorithms, or codes may be converted to a programming language or computer program. A “Programming Language” and “Computer Program” is any-language used to specify instructions to a computer, and includes (but is not limited to) these languages and their derivatives: Machine language, Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, Machine code, operating system command languages, Pascal, Pearl, PU1, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, and fifth generation computer languages. Also included are database and other data schemas, and any other meta-languages. For the purposes of this definition, no distinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. For the purposes of this definition, no distinction is made between compiled and source versions of a program. Thus reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all states. The definition also encompasses the actual instructions and the intent of those instructions.

[0017] Any of the herein described methods, programs, algorithms, or codes may be contained on one or more machine-readable media. The term machine-readable medium may include a mechanism that provides (i.e., stores and/or transmits) information in a form readable by a machine such a processor, computer, or a digital processing device. For example, a machine-readable medium may include a read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, or any other volatile or non-volatile memory storage device. Code or instructions contained thereon can be represented by carrier wave signals, infrared signals, digital signals, and by other like signals.

[0018] According to at least one aspect of the disclosure herein, an electrosurgical system includes an electrosurgical generator configured to provide electrosurgical energy to an electrosurgical device coupled thereto which, in turn, delivers electrosurgical energy to tissue. The electrosurgical device includes a plurality of sensors configured to detect at least one tissue property and output a detected tissue property signal relating thereto. One or more multiplexers having a plurality of channels are electrically connected to each of the corresponding plurality of sensors. The multiplexer(s) may be configured to receive the detected tissue property signal from each sensor of the plurality of sensors and output at least one output signal along one or more signal lines. The one or more signal lines are configured to connect to the electrosurgical generator to control a power output of the electrosurgical generator. A channel select algorithm is configured to automatically select channels from the plurality of channels.

[0019] According to at least one aspect of the disclosure herein the tissue property may be selected from the group consisting of impedance, temperature, electromagnetic field, fluid pressure, fluid flow, tissue density, piezoelectric voltage, and any combination thereof.

[0020] According to another aspect of the disclosure herein, one or more of the plurality of sensors may include a sensor that outputs an analog signal. The electrosurgical system may further include an analog-to-digital converter that accepts an analog signal from one or more of the plurality of sensors and outputs a digital signal to the multiplexer.

[0021] According to another aspect of the disclosure herein, the electrosurgical system may further include an analog-to-digital converter that accepts a signal from the multiplexer(s), and outputs a digital signal to the electrosurgical generator. The channel select algorithm may include a clock and a counter configured to iterate through the channels as a function of time. The channel select algorithm may also include one or more microprocessors programmed to select a desired channel.

[0022] The channel select algorithm may be configured to transmit a binary signal to the multiplexer(s). The multiplexer(s) may be configured to select a desired channel corresponding to the binary signal.

[0023] According to yet another aspect of the disclosure herein, an energy delivery device is configured to direct energy to tissue and includes a plurality of sensors each configured to detect one or more tissue properties and output a detected tissue property signal relating thereto. One or more multiplexers having a plurality of channels are electrically connected to each of the corresponding plurality of sensors, the multiplexer(s) being configured to receive each signal relating to the respective tissue property from each sensor and output one or more output signals along a single signal line A channel select algorithm may be configured to automatically select one or more of the channels from the plurality of channels.

[0024] According to still another aspect of the disclosure herein, a method of controlling the power output of an electrosurgical system is disclosed and includes the step of sensing at least one tissue property using a plurality of sensors disposed on an electrosurgical device to create a plurality detected tissue property signals. The method further includes the steps of receiving the plurality of signals with one or more multiplexers having a plurality of channels electrically connected to each of the corresponding plurality of sensors, the one or more multiplexers configured to receive the plurality of detected tissue property signals from each of the plurality of sensors and output one or more output signals along at least one signal line; outputting a channel select signal to the multiplexer(s); selecting one of the plurality of channels based on the channel select signal; and outputting the selected signal from the multiplexer(s) along the signal line(s).

[0025] The method may further include the step of receiving the detected tissue property signal at a generator control system, the generator control system configured to modify the power output of one or more generators removably connected to the electrosurgical device as a function of the detected tissue property signal.

[0026] The method may include the step of processing the plurality of detected tissue property signals before receiving the plurality of signals at the multiplexer(s).

[0034] Hereinafter, aspects of the presently-disclosed systems for multiplexing signals from sensor packages and methods for using the same are described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[0035] The disclosure herein is directed to electrosurgical devices and systems for performing ablation procedures. An example of an electrosurgical system for performing an ablation procedure is depicted in FIG. 1 that shows a microwave antenna assembly 100 in accordance with one embodiment of the present disclosure. Although FIG. 1 depicts a microwave antenna assembly, the present disclosure is not limited to such an assembly. Any electrosurgical device capable of performing an ablation procedure may be used in conjunction with the embodiments described herein. Antenna assembly 100 may include a radiating portion 12 that is connected by feedline 110 (or shaft) via cable 15 to connector 16, which may further connect the assembly 10 to a power generating source 28, e.g., a microwave or RF electrosurgical generator. Assembly 100, as shown, is a dipole microwave antenna assembly, but other antenna assemblies, e.g., monopole or leaky wave antenna assemblies, may also utilize the principles set forth herein. Distal radiating portion 105 of radiating portion 12 may include a tapered end 120 which terminates at a tip 123 to allow for insertion into tissue with minimal resistance. It is to be understood, however, that tapered end 120 may include other shapes, such as without limitation, a tip 123 that is rounded, flat, square, hexagonal, cylindroconical or any other polygonal shape. An insulating puck 130 may be disposed between distal radiating portion 105 and proximal radiating portion 140. Puck 130 may be formed from any suitable elastomeric or ceramic dielectric material by any suitable process.

[0036] Power generating source 28 includes suitable input controls (e.g., buttons, activators, switches, touch screen, etc.) for controlling the power generating source 28. In addition, the power generating source 28 may include one or more display screens for providing the user with variety of output information (e.g., intensity settings, treatment complete indicators, etc.). The controls allow the user to adjust power of the energy, waveform, as well as the level of maximum energy allowed which varies depending on desired tissue effects and other parameters to achieve the desired waveform suitable for a particular task. Antenna assembly 100 may also include a plurality of input controls that may be redundant with certain input controls of the power generating source 28. Placing the input controls at the antenna assembly 100 allows for easier and faster modification of energy parameters during the ablation procedure without requiring interaction with the power generating source 28.

[0037] As will be described in more detail below, FIGS. 2-6 depict different electrosurgical devices capable of consolidating all sensor-to-generator communication onto a limited number of signal lines. The power supply and ground lines for the sensor packages will be provided by a single power supply line and common ground line to the device from the generator. The electrosurgical devices described herein apply to generators which can read in a limited number of analog or digital sensor lines. As an example, a microwave ablation (MWA) system may have a thermocouple sensor on the device side, which is a passive analog device. The generator is able to see the thermocouple voltage through a twisted wire pair which it amplifies and monitors (one of the wires being a ground or reference line). For a device which has multiple sensor packages, all the sensor data must pass to the generator through this signal analog signal line.

[0038] To consolidate all sensor output signals onto a limited amount of lines, a multiplexer is used within the electrosurgical device handle. All sensors output analog or digital signals that are input into the multiplexer. The multiplexer cycles through the input signals from the sensor packages, according to a channel select algorithm, and outputs the corresponding signal onto the signal line which goes to the generator.

[0039] Referring to FIG. 2, an electrosurgical system 200 includes an electrosurgical device 201 and generator 202. Electrosurgical device 201 includes an ablation antenna 203 for outputting radiation to ablate tissue, e.g., mammalian tissue. Antenna 203 is coupled to generator 202 via a high power transmission line 222. In other embodiments, generator 202 may be integrated into electrosurgical device 201. Generator 202 may have at least one control system for monitoring and controlling power output to antenna 203.Antenna 203 may be optimized for any desired frequency band. Antenna 203 may be removably coupled to electrosurgical device 201 and/or generator 202.

[0040] Electrosurgical device 201 includes a plurality of sensors 204 for detecting one or more tissue properties. Non-limiting examples of at least one of the plurality of sensors 204 may include thermal sensors, electromagnetic field sensors, RF electrode impedance monitors, user interface electronics, fluid pressure sensors, fluid flow sensors, piezoelectric voltage sensors, ultrasound and/or optical sensors for detecting tissue density, and any combinations thereof. The sensors 204 may output an analog electrical signal, a digital signal, or a combination thereof. Each sensor 204 outputs a signal indicative of a detected tissue property or detected property of the ambient environment as an analog electrical signal or a digital signal. The detected properties include, but are not limited to: impedance, temperature, electromagnetic field, tissue density etc.

[0041] One or more of the plurality of sensors may be included in one or more sensor packages 205. In one embodiment, sensor package 205 may include one or more signal processing circuits 206 for conditioning the signal that is output from the sensor. A signal processing circuit 206 may include various integrated circuits and/or discrete components to process the output of sensor 204 such as low noise amplifiers, voltage dividers, etc. In another embodiment, signal processing circuit 206 may be configured to modify the output of each sensor 204 in one or more ways that include, but are not limited to, any type of analog or digital modification or conversion such as amplification and/or analog-to-digital conversion. For example, for sensors that output analog signals, the output of each sensor 204 may be conditioned using an analog signal processing circuit by amplification or analog-to-digital conversion.

[0042] The signal outputted by each sensor 204 may be used to determine if the sensors are functioning properly by measuring the voltage of the signal and comparing the measured voltage to a predetermined voltage. This could be modeled as a step function wherein if the proper voltage is met, the system knows the sensor is working and vice versa. For example, the output of each sensor 204 may be conditioned using an analog signal processing circuit as described above to output 3 volts+/− an acceptable error. If the voltage is read to be outside of this range, then generator 202 may realize there is an error and respond accordingly. In an error situation, a signal may be given to an alert system, such as a light or audio device (not shown) that would notify the user of a faulty sensor or generator may cease delivery of energy to the electrosurgical device 201.

[0043] Multiplexer 207 is electrically coupled to each sensor package 205 and/or analog signal processing circuit 206 and is configured to receive the signals from each sensor package 205. Multiplexer 207 has multiple channels with at least one channel corresponding to each sensor package 205. Multiplexer 207 may be an analog multiplexer, a digital multiplexer, or a combination thereof. Multiplexer 207 outputs a signal along at least one signal line 209. The output signal may be any one or more of the signals generated by the sensor packages 205 and/or analog signal processing circuits 206. Thus, the multiplexer 207 may accept multiple signals, select a channel corresponding to a sensor package 205 or sensor 204, and output an output signal along the limited number of signal lines 209, thus reducing the amount of lines that ultimately connect electrosurgical device 201 to generator 202. As an example, an electrosurgical device 201 may have N sensors 204 and up to N-1 signal lines 209, thus requiring one or more multiplexers 207 as described above to utilize the reduced amount of signal lines 209 relative to the amount of sensors 209.

[0044] Signal line 209 is configured to ultimately connect to generator 202 to provide feedback. Based on the feedback provided by signal line 209, generator 202 controls the energy output of generator 202 to antenna 203. In embodiments, such as that shown in FIG. 2, signal line 209 may connect directly to generator 202 without having to pass through any other stages or may pass through one or more circuits to process the signal. Generator 202 also provides a power line 224 and a reference/ground line 226 to provide power to multiplexer 207, analog signal processing circuits 206, and sensor packages 205.

[0045] Electrosurgical device 201 may also include a channel select system that includes channel select lines 215, a counter 217, and a clock 219. Clock 219 may be a crystal oscillator that outputs a signal at a predetermined frequency. The signal provided by clock 219 is used to increment counter 217 that outputs the required binary representation to select one of the input channels 208 to output a detected tissue property associated with the selected input channel For example, as shown in FIG. 2, counter 217 would output a 3-bit binary signal in the case of an 8 to 1 multiplexer. Clock 219 and counter 217 may be used to cycle through input channels 208 as a function of time.

[0046] The channel select system may include a channel select algorithm for automatically selecting one or more channels. The algorithm may have a selection function such that the multiplexer selects channels as a function of a selected variable including but not limited to time, relative location of the electrosurgical device, any desired tissue property as described herein, temperature, impedance, EM field, or any combination thereof. The algorithm includes computing the selection function, selecting the channel(s), and outputting a signal from the selected channel(s) along the signal line(s).

[0047] Turning to FIG. 3, an electrosurgical system 300 according to another embodiment of the present disclosure is shown generally as 301. In the interest of brevity, the present embodiment will focus on the differences between the previously described electrosurgical system 200 and electrosurgical system 300. Electrosurgical system 300 includes an electrosurgical device 301 electrically coupled to generator 302. During an electrosurgical procedure, i.e. an ablation procedure, a clinician may want to monitor a particular tissue property. By operating the controls on generator 302, the clinician may select the desired tissue property. Then generator 302 may provide a binary signal along channel select lines 315 directly to microprocessor 207 to select an input channel 208 corresponding to the sensor package 205 that detects the desired tissue property.

[0048] Multiplexer 207 then selects the input channel 208 corresponding to the desired tissue property using a channel select system and/or channel select algorithm and outputs an analog detected tissue property signal indicative of the desired tissue property on signal line 309. Signal line 309 may provide the analog signal directly to generator 302 or the analog signal may be converted to a digital signal using an analog to digital (A/D) converter 311 before electrosurgical device 301 outputs the signal to generator 302.

[0049] Turning to FIG. 4, an electrosurgical system according to another embodiment of the present disclosure is shown generally as 400. In the interest of brevity, the present embodiment will focus on the differences between the previously described electrosurgical systems 200, 300 and electrosurgical system 400. Electrosurgical system 400 includes an electrosurgical device 401 coupled to generator 402. Generator 402 provides a reference or ground 422, a power line 424, and a communication line 426. Communication line 426, which will be described in more detail below, is configured to provide a two way digital data stream between generator 402 and microprocessor 413 of electrosurgical device 401.

[0050] Signal line 409 may pass directly or indirectly to one or more microprocessors 413. In some embodiments where the output signal from multiplexer 407 is analog, the signal line 409 may connect to an analog-to-digital converter 411 that converts the analog signal to a digital signal before outputting the signal to microprocessor 413. If the output signal from multiplexer 407 is already digital, then the output signal may pass directly to the microprocessor 413.

[0051] Turning to FIG. 5, an electrosurgical system according to another embodiment of the present disclosure is shown generally as 500 In the interest of brevity, the present embodiment will focus on the differences between the previously described electrosurgical systems 200, 300, 400 and electrosurgical system 500. Electrosurgical system 500 includes an electrosurgical device 501 coupled to generator 502. Generator 402 provides a reference or ground 522, a power line 524, and a communication line 526. Communication line 526, which will be described in more detail below, is configured to provide a two way digital data stream between generator 502 and microprocessor 513 of electrosurgical device 501. In some embodiments, sensor package 505 includes at least one sensor 504 as described above, at least one signal processing circuit 506 as described above, and at least one analog to digital converter 511 as described above. As shown, electrosurgical device includes a multiplexer 507 configured to accept either analog or digital signals from the sensor packages 505 and to output a digital signal along signal line 509 to the microprocessor 513. Microprocessor 513 and multiplexer 507 may be configured to digitally control channel selection of multiplexer 507 channels over the signal line 509, thus reducing the amount of internal hard wiring.

[0052] Turning to FIG. 6, an electrosurgical system according to another embodiment of the present disclosure is shown generally as 600 In the interest of brevity, the present embodiment will focus on the differences between the previously described electrosurgical systems 200, 300, 400, 500 and electrosurgical system 600. Electrosurgical system 600 includes an electrosurgical device 601 coupled to generator 602. Generator 602 provides a reference or ground 622, a power line 624, and a digital signal line 609. Digital signal line 609, which will be described in more detail below, is configured to provide a two way digital data stream between generator 602 and digital multiplexer 607 of electrosurgical device 601. As shown, electrosurgical device 601 includes a multiplexer 607 configured to accept either analog or digital signals from the sensor packages 605 and to output a digital signal directly to the generator 602. In such a case, multiplexer 607 may be integrated with a microprocessor to handle all communication protocol with the generator 602 and to control channel selection of the multiplexer channels.

[0053] Electrosurgical system may one or more generators for supplying energy and one or more generator control systems for controlling a power output of the generator(s). The generator control system(s) may include one or more computer readable media and control software stored thereon. The electrosurgical system may also have an electrosurgical device as described above.

[0054] A two way digital data stream may be created over a signal line or communication line as described above. The two way digital data stream may include data from one or more sensors, from one or more multiplexers, from one or more microprocessors, or from one or more generators.

[0055] Further disclosed is a method of controlling the power output of an electrosurgical device. The method has the step of sensing one or more tissue properties using a plurality of sensors disposed on an electrosurgical device as described above to create a plurality of detected tissue property signals. At least one of the plurality of signals comes from each sensor.

[0056] The method further includes the step of receiving the plurality of analog or digital signals at a multiplexer as described above. In some embodiments, the plurality of input signals may be modified or converted to digital before being received at the multiplexer.

[0057] The method may further include the step of selecting which of the plurality of signals to allow the multiplexer to output by using a channel select system and/or channel select algorithm as described above. For example, the channel select system/algorithm may output a channel select signal to the multiplexer, allowing selection of one of the plurality of signals based on the channel select signal.

[0058] In some embodiments, the method may include outputting a selected analog signal from the multiplexer. In other embodiments, the signal output may be digital.

[0059] The method may further include the step of receiving a data signal at a generator control system. The data signal may be an analog signal or digital signal that either comes from the multiplexer directly or passes through one or more circuit components, modifications, and/or conversions. The generator control system may be configured to modify the power output of one or more generators as a function of the data signal. The generator(s) may be removably connected to the electrosurgical device such that there may be a detachable power supply line, a detachable signal line or communication line as described above, a detachable ground wire, or any combination thereof.

[0060] The method may further include the step of processing the plurality of analog signals as described above before receiving the plurality of analog signals at the multiplexer. In some embodiments, the method further includes the steps of converting an analog signal to a digital signal, and receiving a digital signal at one or more microprocessors as describe above. Again, as described above, the channel select system may be disposed within the electrosurgical device or the generator control system.

[0061] It should be understood that the foregoing description is only illustrative of the present disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications, and variances. The embodiments described with reference to the attached drawing figs. are presented only to demonstrate certain examples of the disclosure. Other elements, steps, methods, and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.