Patent Publication Number: US-2022233090-A1

Title: Techniques for controlling medical device tools

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application No. 63/142,242, filed Jan. 27, 2021; U.S. Provisional Patent Application No. 63/142,247, filed Jan. 27, 2021; U.S. Provisional Patent Application No. 63/142,254, filed Jan. 27, 2021; and U.S. Provisional Patent Application No. 63/142,260, filed Jan. 27, 2021. The subject matter of these related applications is hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Various Embodiments 
     Embodiments of the present disclosure relate generally to electronics and medical diagnostic technology and, more specifically, to techniques for controlling medical device tools. 
     Description of the Related Art 
     In minimally invasive medical procedures, a healthcare provider typically inserts a medical device into the body of a patient and positions the instrument head of the medical device at a target location, such as the location of a tumor. The instrument head usually includes some form of tool, such as and without limitation, a therapeutic drug delivery tool that delivers a therapeutic drug to the target location, an energy delivery tool that delivers energy (e.g., heat or electricity) to the target location, and/or a tissue sample extraction tool that can be used to extract tissue samples from the target location for further evaluation. 
     One problem that exists with many conventional medical devices is that operating a medical device tool at a location within the body of a patient that is different than the desired target location can damage otherwise healthy patient tissue and/or result in the target location not being properly treated. Therefore, conventional medical devices oftentimes include various mechanisms for determining the location of an associated medical device tool within the body of a patient. Some example mechanisms include, without limitation, transmitters that transmit signals that can be used for triangulation and ultrasound-visible materials that are visible in ultrasound imaging. 
     One drawback of the above mechanisms used for determining the location of a medical device tool with the body of a patient is that these mechanisms are oftentimes inaccurate and, accordingly, are insufficient for confirming that a given tool is positioned correctly at a given target location. More specifically, triangulating and ultrasound imaging typically require calibrating the relevant positioning system with respect to both the medical device tool and a mapping of the body of a patient generated, for example, using a medical scan. Errors introduced in the calibration process can produce errors in determining whether the medical device tool is positioned correctly at the target location. Also, any physiological changes within the patient, such as the size, shape, or location of a tumor, between the time when the medical scan is performed and the time when the medical procedure begins can change the target location. Thus, positioning a medical device tool based on a medical scan can result in applying the medical device tool to healthy tissue instead of applying the medical device tool at the target location. 
     As the foregoing illustrates, what is needed in the art are more effective techniques for controlling medical device tools. 
     SUMMARY 
     Embodiments are disclosed for medical devices. In various embodiments, a medical device includes an instrument head that includes one or more electrode pairs and a medical device tool coupled to a conduit, an impedance bridge, and a processor coupled to the impedance bridge and the conduit. 
     Embodiments are disclosed for controlling a medical device. In various embodiments, a method includes recording, at one or more frequencies, one or more impedance measurements associated with one or more electrode pairs included in an instrument head of the medical device; determining, based on the one or more impedance measurements, a tissue type of a portion of tissue contacting the one or more electrode pairs; and performing one or more operations to control a medical device tool included in the instrument head based on the tissue type. 
     At least one technical advantage of the disclosed medical device relative to the prior art is that the disclosed medical device confirms that a medical device tool is positioned at a given target location before activating the medical device tool. For example, the disclosed medical device is able to determine that the tissue type of a portion of tissue contacting the electrodes in the instrument head of the medical device matches the expected tissue type at the target location prior to activating the medical device too. In this manner, the disclosed medical device is able to apply different medical device tools to tissue at various target locations more accurately than conventional medical devices. Consequently, the disclosed medical device can be used to perform various procedures, such as and without limitation, delivering therapeutic drugs or energy or extracting tissue samples, at specific target locations more accurately and reliably relative to what can be achieved with conventional medical devices. These technical advantages provide one or more technological advancements over prior art approaches. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a medical device, according to various embodiments; 
         FIG. 2  is a more detailed illustration of the instrument head of  FIG. 1 , according to various embodiments; 
         FIG. 3  is another detailed illustration of the instrument head of  FIG. 1 , according to various embodiments; 
         FIGS. 4A-B  are detailed illustrations of the electrode pairs of  FIG. 2  in a first configuration, according to various embodiments; 
         FIGS. 5A-B  are detailed illustrations of the electrode pairs of  FIG. 2  in a second configuration, according to various embodiments; 
         FIG. 6  is a more detailed illustration of the external electrical components of  FIG. 1 , according to various embodiments; 
         FIG. 7  is a more detailed illustration of the medical device of  FIG. 1 , according to various embodiments; and 
         FIG. 8  is a flow diagram of method steps for controlling the medical device of  FIG. 1 , according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth to provide a more thorough understanding of the various embodiments. However, in the range of embodiments of the concepts includes some embodiments omitting one or more of these specific details. 
       FIG. 1  illustrates a medical device  100 , according to various embodiments. As shown, the medical device  100  includes, without limitation, an instrument head  108 , wires  104 , and external electrical components  106 . The instrument head  108  is positioned at a target location  102  (e.g., a location of a tumor). While not shown, the instrument head  108  includes, without limitation, one or more electrode pairs, a conduit, and a medical device tool, such as and without limitation, a therapeutic drug delivery tool that delivers a therapeutic drug to the target location  102 , an energy delivery tool that delivers energy to the target location  102 , or a tissue sample extraction tool that extracts a tissue sample from the target location  102  for further evaluation. The external electrical components  106  generate current at various frequencies. The wires  104  conduct the current between the external electrical components  106  and the instrument head  108 . The external electrical components  106  include a processor that measures the impedance of the electrode pair(s) in the instrument head  108  and a portion of tissue at the target location  102  that contacts the electrode pair(s). As described in greater detail below, the medical device  100  determines a tissue type of the portion of tissue contacting the electrode pair(s) based on the impedance measurements. For example and without limitation, based on the impedance measurements, the tissue type of the portion of tissue can be determined to be one of a tumor tissue type or a non-tumor tissue type. 
       FIG. 2  is a more detailed illustration of the instrument head  108  of  FIG. 1 , according to various embodiments. As shown, the instrument head  108  includes, without limitation, an electrode pair  202 , a medical device tool  204 , a catheter  206 , and wires  104 . The electrode pair  202  conducts current, at various frequencies, through a portion of tissue at the target location  102  that contacts the electrode pair  202 . The wires  104  conduct the current between the external electrical components  106  and the electrode pair  202  through the catheter  206 . Although not shown in  FIG. 2 , the medical device includes a conduit that is coupled to the medical device tool  204 , as described in greater detail below. In various embodiments, the medical device tool  204  delivers therapeutic drugs or energy (e.g., carried by a cannula or wires in the catheter  206 ) and/or extracts a tissue sample from a portion of tissue at the target location  102  for further evaluation. The elements of the instrument head  108  allow a healthcare provider to deliver therapeutic drugs or energy to the portion of tissue contacting the electrode pair  202  and/or to extract a tissue sample from the target location  102  for further evaluation. 
       FIG. 3  is a more detailed illustration of the instrument head  108  of  FIG. 2 , according to various embodiments. As shown, the instrument head  108  includes, without limitation, a first electrode pair  202 - 1 , a second electrode pair  202 - 2 , a medical device tool  204 , and a conduit  302 . As shown, the instrument head  108  includes two electrode pairs  202 - 1 ,  202 - 2 ; however the term “electrode pair  202 ,” as used herein, is to be understood to include various embodiments with any number of electrode pairs  202 , including, without limitation, one electrode pair  202  or three or more electrode pairs  202 . In various embodiments, the medical device tool  204  is a therapeutic drug delivery tool that delivers a therapeutic drug, and the conduit  302  includes one or more therapeutic drug delivery conduits that respectively deliver one or more therapeutic drugs to the therapeutic drug delivery tool. In various embodiments, the medical device tool  204  is an energy delivery tool, such as and without limitation a cautery, and the conduit includes one or more wires coupling the energy delivery tool to an energy source. In various embodiments, the medical device tool  204  is a tissue sample extraction tool, and the conduit  302  includes one or more wires coupling the tissue sample extraction tool to an actuator. In various embodiments, the instrument head  108  includes any number of medical device tools  204 , including, without limitation, two or more medical device tools  204  of a similar type or different types. Further, in various embodiments, the instrument head  108  includes any number of conduits  302 , including, without limitation, two or more conduits. In various embodiments, each conduit  302  is coupled to one or more medical device tools  204 , and/or each medical device tool  204  is coupled to one or more conduits  302 . 
       FIGS. 4A-B  are detailed illustrations of the electrode pairs  202  of  FIG. 2  in a first configuration, according to various embodiments. As shown, the instrument head  108  includes, without limitation, a first electrode pair  202 - 1 , a second electrode pair  202 - 2 , and a medical device tool  204 . As shown, the electrode pairs  202 - 1 ,  202 - 2  extend in a direction that is substantially parallel to an axis of the medical device tool. As also shown, the medical device tool  204  resides in between the electrodes of the electrode pairs  202 - 1 ,  202 - 2  when viewed in a direction of an axis of the medical device tool  204 . 
     As shown in  FIG. 4A , the medical device tool  204  is in a retracted position, in which tips of the electrodes of the electrode pairs  202 - 1 ,  202 - 2  extend in the direction of the axis farther than a tip of the medical device tool  204 . For example and without limitation, the medical device tool  204  can be in the retracted position during deployment and until a processor determines the tissue type of the portion of tissue contacting the electrode pairs  202 - 1 ,  202 - 2 . 
     As shown in  FIG. 4B , the medical device tool  204  extends from the retracted position to an extended position, in which the tip of the medical device tool  204  extends in the direction of the axis at least as far as the tips of the electrodes of the electrode pairs  202 - 1 ,  202 - 2 . For example and without limitation, based on determining the tissue type of the portion of tissue contacting the electrode pairs  202 - 1 ,  202 - 2 , a processor can cause the medical device tool  204  to extend from the retracted position to the extended position (e.g., by activating an actuator that is coupled to the medical device tool  204  and that causes the medical device tool  204  to extend from the retracted position to the extended position). 
       FIGS. 5A-B  are detailed illustrations of the electrode pairs  202  of  FIG. 2  in a second configuration, according to various embodiments. As shown, the instrument head  108  includes, without limitation, a first electrode pair  202 - 1 , a second electrode pair  202 - 2 , and a medical device tool  204 . As also shown, the medical device tool  204  resides in between the electrodes of the electrode pairs  202 - 1 ,  202 - 2  when viewed in a direction of an axis of the medical device tool  204 . 
     As shown in  FIG. 5A , the medical device tool  204  is in a retracted position, in which tips of the electrodes of the electrode pairs  202 - 1 ,  202 - 2  extend in the direction of the axis farther than a tip of the medical device tool  204 . For example and without limitation, the medical device tool  204  can be in the retracted position during deployment and until a processor determines the tissue type of the portion of tissue contacting the electrode pairs  202 - 1 ,  202 - 2 . 
     As shown in  FIG. 5B , the medical device tool  204  extends from the retracted position to an extended position, in which the tip of the medical device tool  204  extends in the direction of the axis at least as far as the tips of the electrodes of the electrode pairs  202 - 1 ,  202 - 2 . For example and without limitation, based on determining the tissue type of the portion of tissue contacting the electrode pairs  202 - 1 ,  202 - 2 , a processor can cause the medical device tool  204  to extend from the retracted position to the extended position (e.g., by activating an actuator that is coupled to the medical device tool  204 ). 
     While not shown, in various embodiments, the electrode pairs  202  can extend and retract in a corresponding manner as the medical device tool  204  in the first configuration shown in  FIGS. 4A-B  or in the second configuration shown in  FIGS. 5A-B . In various embodiments, one or more electrode pairs  202  can be in an extended position, in which the tips of the electrodes of the electrode pairs  202  extend in a direction of an axis of the medical device tool  204  farther than a tip of the medical device tool  204 . In various embodiments, the electrode pairs  202  are in the extended position during deployment and until a processor determines the tissue type of the portion of tissue contacting the electrode pairs  202 . In various embodiments, based on the determined tissue type, the electrode pairs  202  retracts from the extended position to a retracted position, in which the tip of the medical device tool  204  extends in the direction of the axis at least as far as the tips of the electrode pairs  202 . For example and without limitation, based on determining the tissue type of the portion of tissue contacting the electrode pairs  202 , a processor can cause one or more electrodes pairs to retract from the extended position to the retracted position (e.g., by activating an actuator that is coupled to the one or more electrode pairs  202 ). As shown, the respective electrodes of the electrode pairs  202 - 1 ,  202 - 2  are curved to extend laterally outward with respect to the axis of the medical device tool  204 . In various embodiments, at least one electrode of the one or more electrode pairs  202 - 1 ,  202 - 2  is made from a flexible material. In various embodiments, a processor can cause the medical device tool  204  to extend from a retracted position to an extended position and also cause the electrode pairs  202  to retract from an extended position to a retracted position. For example and without limitation, based on determining the tissue type of the portion of tissue, a processor can activate an actuator to cause the medical device tool  204  to extend, and also activate an actuator to cause the electrode pairs  202  to retract. 
     As technical advantages of these various embodiments, in various embodiments and without limitation, causing the medical device tool  204  to be in a retracted position until confirming that the medical device  100  is positioned at the target location  102 , and then to extend, can prevent the medical device tool  204  from contacting other tissue of the patient. Similarly, causing the electrode pairs  202  to be in an extended position until confirming that the medical device  100  is positioned at the target location  102 , and then to retract, can prevent the medical device tool  204  from contacting other tissue of the patient. Alternatively or additionally, in various embodiments and without limitation, causing the electrode pairs  202  to retract, and/or causing the medical device tool  204  to extend, can prevent the medical device tool  204  from altering the impedance measurements of the portion of tissue at the target location  102  by the electrode pairs  202 . Alternatively or additionally, in various embodiments and without limitation, causing the electrode pairs  202  to retract, and/or causing the medical device tool  204  to extend, can prevent the medical device tool  204  from contacting the electrode pairs  202  during operations (e.g., while the medical device tool  204  delivers a therapeutic drug, delivers energy, extracts a tissue sample, or the like). Further, in various embodiments in which electrodes extend laterally outward with respect to the axis of the medical device tool  204 , extending the electrode pairs  202  can cause the electrodes to contact a larger portion of tissue (e.g., impedance measurements of a large tumor), while retracting the electrode pairs  202  can cause the electrodes to contact a smaller portion of tissue (e.g., impedance measurements of a small tumor). 
       FIG. 6  is a more detailed illustration of the external electrical components of  FIG. 1 , according to various embodiments. As shown, the external electrical components  106  include wires  104 , an amplifier  602 , an impedance bridge  604 , and a processor  606 . The wires  104  conduct current at various frequencies between an electrode pair  202  and the external electrical components  106 . In various embodiments, the amplifier  602  is an analog interface amplifier that amplifies a supplied voltage and/or a return voltage while the wires  104  conduct current at various frequencies between the impedance bridge  604  and the electrode pair  202 . In various embodiments, the impedance bridge  604  is an impedance load that the processor  606  measures to determine an impedance of a circuit including the impedance bridge  604 , the amplifier  602 , and the electrode pair  202 . The processor  606  generates frequencies for a current that the wires  104  conduct between the impedance bridge  604  and the electrode pair  202 . 
     While the wires  104  conduct current at various frequencies, the processor  606  records one or more impedance measurements  608  of the circuit including the electrode pair  202 . The processor  606  determines a tissue type  610  of a portion of tissue contacting the electrode pair  202  based on the impedance measurements  608 . In various embodiments, the processor  606  determines the tissue type  610  by comparing the impedance measurements  608  with one or more characteristic impedance measurements associated with one or more tissue types. For example and without limitation, based on the comparing, the processor  606  can determine which tissue type is associated with characteristic impedance measurements that are closest to the impedance measurements of the portion of tissue contacting the electrode pair  202 . In various embodiments, the processor  606  can determine a Cole relaxation frequency of the portion of tissue based on the impedance measurements  608 , and can compare the Cole relaxation frequency to one or more characteristic Cole relaxation frequencies of one or more tissue types. The Cole relaxation frequency corresponds to a frequency associated with a greatest impedance measurement  608  included in the one or more impedance measurements  608 . In various embodiments, the Cole relaxation frequency is a frequency of a maximum normalized impedance measurement of the portion of tissue contacting the electrode pair  202 . For example and without limitation, based on a Cole relaxation frequency below a threshold frequency (e.g., 10 5  Hz), the processor  606  can determine that the portion of tissue contacting the electrode pair  202  is a non-tumor tissue type. Similarly, for example and without limitation, based on a Cole relaxation frequency above the threshold frequency, the processor  606  can determine that the portion of tissue contacting the electrode pair  202  is a tumor tissue type. 
     In various embodiments, the processor  606  performs one or more operations  612  to control the medical device tool  204  based on the determined tissue type  610 . For example and without limitation, in various embodiments in which the medical device tool  204  is a therapeutic drug delivery tool, the processor  606  can perform operations  612  that include activating the therapeutic drug delivery tool to deliver one or more therapeutic drugs to the portion of tissue. For example and without limitation, in various embodiments in which the medical device tool  204  is an energy delivery tool, the processor  606  can perform operations  612  that include activating the energy delivery tool to deliver energy to the portion of tissue. For example and without limitation, in various embodiments in which the medical device tool  204  is a tissue sample extraction tool, the processor  606  can perform operations  612  that include activating the tissue sample extraction tool to extract a tissue sample from the portion of tissue. For example and without limitation, in various embodiments in which the medical device tool  204  can extend, the processor  606  can perform operations  612  that include causing the medical device tool  204  to extend from a retracted position to an extended position (e.g., by activating an actuator that is coupled to the medical device tool  204 ). For example and without limitation, in various embodiments in which the electrode pair  202  can retract, the processor  606  can perform operations  612  that include causing the electrode pair  202  to retract from an extended position to a retracted position (e.g., by activating an actuator that is coupled to the electrode pair  202 ). 
     In various embodiments, based on determining the tissue type  610 , the processor  606  presents an indication of the tissue type  610  of the portion of tissue contacting the electrode pair  202 . For example and without limitation, the processor  606  can indicate the tissue type  610  using a visual output (e.g., a light-emitting diode, a liquid crystal display, or the like) and/or an audio output (e.g., a speaker, a buzzer, or the like). In various embodiments, based on determining the tissue type  610 , the processor  606  presents an indication that the determined tissue type  610  matches the tissue type of tissue at a target location  102 . For example and without limitation, where the target location  102  is a tumor, the processor  606  can indicate that a determined tumor tissue type matches the tissue type of the tissue at the target location  102 . Presenting the indication can inform a user of the medical device  100  that the instrument head is at the target location  102 . Further, in various embodiments, the processor  606  performs the one or more operations  612  to control the medical device tool  204  based on presenting the indication that the determined tissue type  610  matches the tissue type of tissue at a target location  102  and receiving a signal to activate the medical device tool  204 . 
       FIG. 7  is a more detailed illustration of the medical device  100  of  FIG. 1 , according to various embodiments. As shown, the medical device  100  includes an instrument head  108  and external electrical components  106 . As shown, the instrument head  108  includes an electrode pair  202  that is coupled to the external electrical components  106  by wires  104 . In various embodiments, the instrument head  108  includes, without limitation, two or more electrode pairs  202 , which can be coupled to the external electrical components  106  by one wire  104  or by respective wires of a plurality of wires  104 . As shown, the instrument head  108  also includes a medical device tool  204 , such as and without limitation, a therapeutic drug delivery tool, an energy delivery tool, or a tissue sample extraction tool. In various embodiments, the instrument head  10  includes, without limitation, two or more medical device tools  204 , which can be of one kind or of different kinds. 
     As shown, the external electrical components  106  include an amplifier  602 , an impedance bridge  604 , and a processor  606 . The amplifier  602  amplifies a supplied voltage and/or a return voltage while the wires  104  conduct current at various frequencies between the impedance bridge  604  and the electrode pair  202 . The impedance bridge  604  is an impedance load that the processor  606  measures to determine an impedance of a circuit including the impedance bridge  604 , the amplifier  602 , the wires  104 , and the electrode pair  202 . The processor  606  records, at various frequencies, one or more impedance measurements  608 . The processor  606  determines a tissue type  610  of a portion of tissue contacting the electrode pair  202  based on the impedance measurements  608 . In various embodiments and without limitation, the processor  606  determines the tissue type based on a Cole relaxation frequency of the portion of tissue contacting the electrode pair  202 . In various embodiments and without limitation, the processor  606  determines the tissue type  610  of the portion of tissue as one of a tumor tissue type or a non-tumor tissue type. In various embodiments and without limitation, the processor  606  determines that the tissue type  610  matches the tissue type of tissue at the target location  102 , which indicates or confirms that the instrument head  108  is positioned at the target location  102 . For example and without limitation, if the target location  102  is a tumor, the processor  606  can determine whether the instrument head  108  is positioned at the target location  102  by determining that the tissue type  610  is a tumor tissue type. 
     As shown, the processor  606  is coupled to a conduit  302  of the medical device tool  204 . Based on the determined tissue type  610 , the processor  606  performs one or more operations  612  to control the medical device tool  204 . In various embodiments and without limitation, the medical device tool  204  is a therapeutic drug delivery tool, and the processor  606  performs an operation  612  of causing the medical device tool  204  to deliver one or more therapeutic drugs to tissue at the target location  102 . For example and without limitation, the processor  606  can cause one or more therapeutic drugs through one or more drug delivery conduits to and through the therapeutic drug delivery tool. In various embodiments and without limitation, the medical device tool  204  is an energy delivery tool, and the processor  606  performs an operation  612  of causing the conduit  302  and the medical device tool  204  to deliver energy to tissue at the target location  102 . For example and without limitation, the processor  606  can current to be conducted through wires in the conduit  302  to and through the energy delivery tool. In various embodiments and without limitation, the medical device tool  204  is a tissue sample extraction tool, and the processor  606  performs an operation  612  of causing the tissue sample extraction tool to extract a tissue sample from tissue at the target location  102 . For example and without limitation, the external electrical components  106  can include an actuator coupled to the tissue sample extraction tool by wires in the conduit  302 , and the processor  606  can activate the actuator to cause the tissue sample extraction tool to extract the tissue sample. 
     In various embodiments, the medical device  100  reports the determined tissue type  610  to a user of the medical device  100 . For example and without limitation, the medical device  100  can display an indicator of the determined tissue type  610  using a visual output (e.g., a liquid crystal display (LCD), a light-emitting diode (LED) display to present a visual indication of the tissue type  610 , such as a light, symbol, text, graphic, or the like) and/or an audio indication of the determined tissue type  610  using an audio output (e.g., using a speaker, buzzer, or the like to present an audio cue of the tissue type  610 , such as a spoken description, sound effect, or the like). In various embodiments and without limitation, the processor  606  can present an indication that the determined tissue type  610  matches the tissue type of tissue at the target location  102  (e.g., using a visual output, an audio output, or the like). 
       FIG. 8  is a flow diagram of method steps for controlling the medical device  100  of  FIG. 1 , according to various embodiments. Although the method steps are described in conjunction with the systems of  FIGS. 1-7 , persons skilled in the art will understand that any system configured to perform the method steps, in any order, falls within the scope of the present invention. 
     As shown, a method  800  begins at step  802 , where a processor  606  records, at one or more frequencies, one or more impedance measurements  608  associated with one or more electrode pairs  202  included in an instrument head  108  of the medical device  100 . In various embodiments and without limitation, the processor  606  determines a Cole relaxation frequency of a portion of tissue contacting the one or more electrode pairs  202  in the instrument head  108 , e.g., as a frequency of a maximum normalized impedance measurement of the portion of tissue contacting the electrode pair  202 . 
     At step  804 , the processor  606  determines, based on the one or more impedance measurements  608 , a tissue type  610  of a portion of tissue contacting the one or more electrode pairs  202 . In various embodiments and without limitation, the processor  606  determines the tissue type as one of a tumor tissue type or a non-tumor tissue type. In various embodiments and without limitation, the processor  606  determines whether the tissue type of the portion of tissue matches a tissue type of tissue at a target location  102 . In various embodiments, the processor  606  determines the tissue type  610  by comparing the impedance measurements  608  to one or more characteristic impedance measurements associated with one or more tissue types. In various embodiments and without limitation, the processor  606  determines whether the determined tissue type  610  matches a tissue type of tissue at a target location  102  (e.g., in order to determine whether the instrument head  108  is positioned at the target location  102 ). 
     At step  806 , the processor  606  performs one or more operations  612  to control a medical device tool  204  included in the instrument head  108  based on the tissue type  610 . For example and without limitation, based on the determined tissue type  610 , the processor  606  can perform operations  612  that cause a therapeutic medical device tool to deliver a therapeutic drug to tissue at the target location  102 ; that cause an energy device tool to deliver energy to tissue at the target location  102 ; and/or to cause a tissue sample extraction tool to extract a tissue sample from tissue at the target location  102 . In various embodiments, the processor  606  can use one or more of a visual output or an audio output to present an indication of the determined tissue type  610  of the portion of tissue, and/or an indication that the determined tissue type  610  matches the tissue type of tissue at a target location  102 . 
     In sum, the disclosed medical device measures the impedance of a portion of tissue in contact with the electrodes included in the instrument head and residing at a target location. The medical device further determines the tissue type of the portion of tissue based on the measured impedance. Based on the tissue type, the medical device controls a medical device tool in the instrument head and ensures that the medical device tool is applied properly to the portion of tissue at the target location. The disclosed approach advantageously results in the medical device applying the medical device tool to tissue at a target location while avoiding portions of tissue residing at other locations. 
     At least one technical advantage of the disclosed medical device relative to the prior art is that the disclosed medical device confirms that a medical device tool is positioned at a given target location before activating the medical device tool. For example, the disclosed medical device is able to determine that the tissue type of a portion of tissue contacting the electrodes in the instrument head of the medical device matches the expected tissue type at the target location prior to activating the medical device too. In this manner, the disclosed medical device is able to apply different medical device tools to tissue at various target locations more accurately than conventional medical devices. Consequently, the disclosed medical device can be used to perform various procedures, such as and without limitation, delivering therapeutic drugs or energy or extracting tissue samples, at specific target locations more accurately and reliably relative to what can be achieved with conventional medical devices. These technical advantages provide one or more technological advancements over prior art approaches. 
     1. In some embodiments, a medical device comprises an instrument head that includes one or more electrode pairs, and a medical device tool coupled to a conduit; an impedance bridge; and a processor coupled to the impedance bridge and the conduit. 
     2. The medical device of clause 1, wherein the medical device tool comprises a therapeutic drug delivery tool, and the conduit includes one or more therapeutic drug delivery conduits. 
     3. The medical device of clauses 1 or 2, wherein the medical device tool comprises an energy delivery tool, and the conduit includes one or more wires coupling the energy delivery tool to an energy source. 
     4. The medical device of any of clauses 1-3, wherein the medical device tool comprises a tissue sample extraction tool, and the conduit includes one or more wires coupling the tissue sample extraction tool to an actuator. 
     5. The medical device of any of clauses 1-4, wherein the medical device tool resides in between the electrodes of at least one electrode pair. 
     6. The medical device of any of clauses 1-5, wherein at least one electrode of a given electrode pair extends laterally outward with respect to an axis of the medical device tool. 
     7. The medical device of any of clauses 1-6, wherein at least one electrode of a given electrode pair is made from a flexible material. 
     8. The medical device of any of clauses 1-7, further comprising one or more actuators that are coupled to a given electrode pair. 
     9. The medical device of any of clauses 1-8, further comprising an actuator coupled to the medical device tool that causes the medical device tool to extend from a retracted position to an extended position. 
     10. In some embodiments, a method for controlling a medical device comprises recording, at one or more frequencies, one or more impedance measurements associated with one or more electrode pairs included in an instrument head of the medical device; determining, based on the one or more impedance measurements, a tissue type of a portion of tissue contacting the one or more electrode pairs; and performing one or more operations to control a medical device tool included in the instrument head based on the tissue type. 
     11. The method of clause 10, wherein determining the tissue type comprises comparing the one or more impedance measurements to one or more characteristic impedance measurements associated with one or more tissue types. 
     12. The method of clauses 10 or 11, wherein determining the tissue type comprises determining a Cole relaxation frequency of the portion of tissue based on the one or more impedance measurements, and comparing the Cole relaxation frequency of the portion of tissue to one or more characteristic Cole relaxation frequencies of one or more tissue types. 
     13. The method of any of clauses 10-12, wherein the Cole relaxation frequency corresponds to a frequency associated with a greatest impedance measurement included in the one or more impedance measurements. 
     14. The method of any of clauses 10-13, wherein determining the tissue type comprises determining a tumor tissue type based on the Cole relaxation frequency of the portion of tissue being above a threshold frequency, or determining a non-tumor tissue type based on the Cole relaxation frequency of the portion of tissue being below the threshold frequency. 
     15. The method of any of clauses 10-14, wherein the medical device tool comprises a therapeutic drug delivery tool, and performing the one or more operations to control the medical device tool comprises activating the therapeutic drug delivery tool to deliver one or more therapeutic drugs to the portion of tissue. 
     16. The method of any of clauses 10-15, wherein the medical device tool comprises an energy delivery tool, and performing the one or more operations to control the medical device tool comprises activating the energy delivery tool to deliver energy to the portion of tissue. 
     17. The method of any of clauses 10-16, wherein the medical device tool is a tissue sample extraction tool, and performing the one or more operations comprises activating the tissue sample extraction tool to extract a tissue sample from the portion of tissue. 
     18. The method of any of clauses 10-17, wherein performing the one or more operations to control the medical device tool at least one of, causing the medical device tool to extend from a retracted position to an extended position, or causing the electrodes of at least one electrode pair to retract from an extended position to a retracted position. 
     19. The method of any of clauses 10-18, further comprising outputting at least one of a visual indication or an audio indication of the tissue type of the portion of tissue. 
     20. The method of any of clauses 10-19, further comprising outputting at least one of a visual indication or an audio indication that the tissue type of the portion of tissue matches the tissue type of tissue at a target location. 
     Any and all combinations of any of the claim elements recited in any of the claims and/or any elements described in this application, in any fashion, fall within the contemplated scope of the present invention and protection. 
     The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. 
     Aspects of the present embodiments may be embodied as a system, method or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “module,” a “system,” or a “computer.” In addition, any hardware and/or software technique, process, function, component, engine, module, or system described in the present disclosure may be implemented as a circuit or set of circuits. Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. 
     Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine. The instructions, when executed via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks. Such processors may be, without limitation, general purpose processors, special-purpose processors, application-specific processors, or field-programmable gate arrays. 
     The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. 
     While the preceding is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.