Method and system for detecting liquid immersion of an end effector of an ultrasonic instrument

Abstract

A method performed by a surgical system. The method determines one or more characteristics of an end effector of an ultrasonic instrument and, based on the determined one or more characteristics, determines that the end effector is at least partially immersed in a liquid. In response, the method displays a notification indicating that the end effector is at least partially immersed in the liquid on a display of the surgical system.

Description

Technical Field

[0001] Various aspects of the present disclosure generally relate to surgical systems, and more specifically to surgical systems for detecting immersion of an ultrasonic instrument. Other aspects are also described.

Background Art

[0002] Minimally invasive surgery (MIS) such as laparoscopic surgery uses techniques aimed at reducing tissue damage during a surgical procedure. Laparoscopic procedures typically require creating a number of small incisions in a patient, for example, in the patient's abdomen, and then inserting several surgical tools such as an endoscope, a blade, a grasper, and a needle through these incisions into the patient. Gas is injected into the abdomen, which causes the abdomen to expand, thereby providing more space around the tip of the tool and making it easier for the surgeon to view and manipulate the tissue at the surgical site (via the endoscope). MIS can be performed more quickly and with less fatigue for the surgeon using a surgical robotic system in which surgical tools are operably attached to the distal ends of robotic arms and a control system actuates the arms and the tools attached thereto. The tip of the tool mimics the movement of the position and orientation of the UID when a hand-held user input device (UID) is being operated by the surgeon. The surgical robotic system may have a plurality of surgical arms, and one or more of the plurality of surgical arms may have an attached endoscope, and the other surgical arms may have attached surgical instruments for performing a certain surgical action.

[0003] Control inputs from a user (e.g., a surgeon or other operator) are captured via one or more user input devices and then converted into control of the robotic system. For example, in response to a user command, a tool drive having one or more motors may actuate one or more degrees of freedom of a surgical tool when the surgical tool is positioned at the surgical site of the patient.

Summary of the Invention

Means for Solving the Problems

[0004] Some surgical tools used in MIS procedures are ultrasonic instruments that use ultrasonic vibrations at their tips to rapidly generate heat for cutting and cauterizing tissue. The tip may include a blade that reaches a high temperature (e.g., above 300 °C) during a "heating" cycle in which the blade oscillates in contact with a portion of the tissue, thereby generating heat by friction between the blade and the tissue during oscillation. After reaching the high temperature, the blade may be used to incise a portion of the tissue and at the same time seal the remaining tissue. By performing multiple tasks (e.g., cutting for incision, cauterization, etc.), the use of the tool during laparoscopic surgery reduces the number of instrument exchanges and instruments during the procedure.

[0005] The present disclosure provides a laparoscopic surgical system that estimates the temperature of a blade of an ultrasonic instrument during heating and cooling cycles of the blade. Specifically, the system may activate the instrument by providing power to oscillate the blade of the instrument (e.g., in response to receiving user input by an operator, such as pressing a petal or button) when the instrument is used to incise tissue. While the instrument is operating in this “high power” state, the system may determine the temperature of the blade based on one or more characteristics of the instrument (e.g., input voltage, input current, resonance frequency, etc.). After the heating cycle has ended (e.g., after the operator releases the petal), the system may enter a “low power” state (or cooling cycle), in which the ultrasonic instrument may draw less power to cause less blade vibration than while the instrument was in the high power state (e.g., less current may be supplied). While in this low power state, the instrument may not draw enough power to generate frictional heat (e.g., due to the blade vibrating over a lower range of motion than is required to generate heat), but may have enough power to determine one or more characteristics of the instrument, such as the resonance frequency of the blade, that the system can use to estimate the temperature of the ultrasonic instrument while the ultrasonic instrument is cooling. As a result, the system may provide the operator with (e.g., continuous) temperature readings of the ultrasonic instrument between the heating and cooling cycles.

[0006] The temperature estimation value of the ultrasonic device may be affected when the blade of the device is in contact with tissue and / or when it is immersed in a liquid (e.g., blood, physiological saline, etc.). As described in this specification, the temperature estimation value of the blade may be based on the resonance frequency of the blade. However, when the blade is immersed in a liquid and / or when it is in contact with an object, the resonance frequency of the blade may change (e.g., due to an increase in the rigidity of the blade). As a result, the surgical system may not be able to effectively estimate the temperature of the end effector. Therefore, in order to appropriately and effectively estimate the temperature of the end effector, a surgical system that detects the state of the end effector of the ultrasonic device (e.g., whether the end effector is immersed in a liquid and / or whether it is in contact with an object) is needed.

[0007] In addition, when at least a part of the end effector (e.g., the blade) is at least partially immersed in a liquid and / or when it is in contact with an object, the surgical system needs to notify (warn) the operator of the system. As described in this specification, when the ultrasonic device switches from a heating cycle to a cooling cycle, the blade may become too hot to contact tissue. However, during a surgical operation, the operator may have minimal visibility of the heated end effector. As a result, the operator may not be able to visually identify whether the end effector is in contact with something when the end effector cools.

[0008] The present disclosure provides a surgical system that detects when an ultrasonic instrument is in contact with an object (e.g., tissue) and / or is at least partially immersed in a liquid and warns an operator. Specifically, the system determines one or more characteristics of an end effector of the ultrasonic instrument (e.g., while in a low-power state and being cooled). For example, the characteristic may be the impedance of the end effector. The system determines, based on the one or more characteristics, that the end effector is at least partially immersed in the liquid (and / or in contact with an object such as tissue). In response, the system displays a notification indicating that the end effector is immersed in the liquid (and / or in contact with the object) on a display of the surgical system. As a result, the system can warn the operator of the state of the end effector to avoid the operator touching an object while the blade is still hot.

[0009] In one aspect, the one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed includes determining that the impedance exceeds an impedance threshold. In another aspect, the one or more characteristics include the resonant frequency of the end effector, and determining that the end effector is at least partially immersed further includes determining that the resonant frequency is less than a resonant frequency threshold. In some aspects, the system determines the type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, and the notification indicates the type of liquid.

[0010] In one aspect, one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed in a liquid includes determining that the impedance exceeds a first threshold. The system further determines that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold. In some aspects, the notification indicates that the end effector is in contact with an object while immersed in the liquid.

[0011] In another aspect, while the end effector is in air, the system determines the temperature of the end effector, displays the temperature on a display, and replaces the temperature with an estimated temperature of the liquid in response to determining that the end effector is at least partially immersed in the liquid. As a result, the surgical system may estimate and display the temperature of the end effector based on whether the blade is immersed in the liquid and / or in contact with an object.

[0012] The above summary does not include an exhaustive list of all aspects of the present disclosure. The present disclosure is intended to include all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the following "Detailed Description of the Invention", particularly those pointed out in the "Claims". Such combinations may have specific advantages not specifically described in the above summary.

Brief Description of the Drawings

[0013] Aspects are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals indicate like elements. Note that references to “an” or “one” aspect in this disclosure are not necessarily to the same aspect, and they mean at least one. Also, for purposes of brevity and reducing the total number of figures, a given figure may be used to illustrate features of more than one aspect, and not all elements in a figure may be required for a given aspect.

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0014] Reference will now be made to the accompanying drawings to describe some aspects of the present disclosure. Whenever the shape, relative position, and other aspects of the parts described in a given aspect are not explicitly defined, the scope of the disclosure in this specification is not limited only to the parts shown, which are merely for illustrative purposes. Also, although numerous details are described, it is understood that some aspects can be practiced without these details. In other cases, well-known circuits, structures, and techniques are not shown in detail so as not to obscure the understanding of this description. Further, unless the meaning is clearly contrary, all ranges described in this specification are considered to include the endpoints of each range.

[0015] FIG. 1 shows a depiction of an exemplary (e.g., laparoscopic) surgical system 1 (hereinafter sometimes referred to as the “system”) in an operating room. The system 1 includes a user console 2, a control tower 3, and one or more surgical robot arms 4 on a surgical robot table (surgical table or surgical platform) 5. In one aspect, the arm 4 may be mounted on a table or bed on which the patient lies, as shown in the embodiment of FIG. 1. In one aspect, at least some of the arms 4 may be configured differently. For example, at least some of the arms may be mounted on another suitable structural support such as a ceiling, a side wall, or a cart separate from the table. The system 1 may incorporate any number of devices, tools, or accessories used to perform surgery on the patient 6. For example, the system 1 may include one or more surgical tools (instruments) 7 used to perform a surgery (surgical procedure). The surgical tool 7 may be an end effector attached to the distal end of the surgical arm 4 for performing a surgical procedure.

[0016] Each surgical tool 7 may be operated manually, robotically, or both during a surgery. For example, the surgical tool 7 may be a tool used to enter, view, or manipulate the internal anatomical structure of the patient 6. In one aspect, the surgical tool 7 is a gripper that can grip the patient's tissue. The surgical tool 7 may be manually controlled by an operator 8 beside the bed or may be robotically controlled via the actuated movement of a surgical robot arm 4 to which the surgical tool is attached. For example, when manually controlled, the operator may (e.g., physically) hold a portion of the tool (e.g., the handle) and manually control the tool by moving the handle and / or pressing one or more input control parts (e.g., buttons) on the tool (e.g., the handle of the tool). In another aspect, when robotically controlled, the surgical system may manipulate a surgical tool-based user input (e.g., received via the user console 2 as described herein).

[0017] Generally, a remote operator 9, such as a surgeon or other operator, may use the user console 2 to remotely operate the arm 4 and / or the attached surgical tool 7, for example, during teleoperation. The user console 2 may be located in the same operating room as the rest of the system 1, as shown in FIG. 1. However, in other environments, the user console 2 may be located in an adjacent or nearby room, or in a remote location, such as a different building, city, or country. The user console 2 may include one or more components, such as a seat 10, one or more foot-operated controls (or foot pedals) 13, one or more (handheld) user input devices (UIDs) 14, and at least one display 15. The display is configured to display, for example, a view of the surgical site inside the patient 6. The display may be configured to display image data (e.g., still images and / or videos). In one aspect, the display may be any type of display, such as, for example, a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, etc. In some aspects, the display may be a 3D immersive display for displaying 3D (surgical) representations. For example, during a surgical procedure, one or more endoscope cameras may capture image data of the surgical site that the display presents to the user in 3D. In one aspect, the 3D display may be a naked-eye stereoscopic display that provides 3D perception to the user without the need for special glasses. As another example, the 3D display may be a stereoscopic display that provides 3D perception using glasses (e.g., via active shutter or polarization).

[0018] In another aspect, the display 15 may be configured to be displayed in the last graphical user interface (GUI) that can provide useful and / or interactive content, thereby assisting the user in performing a surgical procedure using one or more instruments within the surgical system 1. For example, some of the displayed content may include image data captured by one or more endoscopic cameras, as described herein. In another aspect, the GUI may include selectable UI items that can cause the system to perform one or more operations when operated by the user. For example, the GUI may include UI items as interactive content for switching control between robotic arms. In one aspect, to interact with the GUI, the system may include an input device, such as a keyboard, mouse, etc. In another aspect, the user may interact with the GUI using the UID 14. For example, the user may operate the UID to navigate through the GUI (e.g., using a cursor), and to make a selection, overlay the cursor on a UI item and operate the UID (e.g., select a control or button). In some aspects, the display may be a touch display screen. In this case, the user may make a selection by navigating and selecting through touching the display. In some aspects, any method may be used to navigate and / or select UI items.

[0019] As shown, the remote operator 9 is sitting on the seat 10, looking at the user display 15 while operating the foot pedal control 13 and the handheld UID 14 to remotely control one or more of the arm 4 and the surgical tool 7 (mounted to the distal end of the arm 4).

[0020] In some variations, the operator 8 beside the bed may also operate the system 1 in the "bed-facing" mode. In this mode, the operator 8 (user) beside the bed is here beside the patient 6 and, for example, is operating a robot-driven tool (the end effector attached to the arm 4) held in one hand with a handheld UID 14 while simultaneously operating a manual laparoscopic tool. For example, the left hand of the operator beside the bed may be operating the handheld UID to control the robotic components, while the right hand of the operator beside the bed may be operating the manual laparoscopic tool. Thus, in these variations, the operator 8 beside the bed may perform both robot-assisted minimally invasive surgery and manual laparoscopic surgery on the patient 6.

[0021] During an exemplary procedure (surgery), the patient 6 is sterilized, prepared, and covered to achieve anesthesia. The initial access to the surgical site may be performed manually, during which the arm of the system 1 is in a stowed or retracted configuration (thereby facilitating access to the surgical site). When the access is complete, an initial positioning or preparation of the system 1 including its arm 4 may be performed. Next, the remote operator 9 at the user console 2 uses the foot pedal control 13 and the UID 14 to operate various end effectors and perhaps an imaging system to perform the surgery and thereby advance the surgery. Manual assistance may also be provided at the treatment bed or table by a person beside the bed wearing a sterile gown, for example, the operator 8 beside the bed, and the operator 8 may perform tasks such as retracting tissue, performing manual repositioning, and exchanging one or more tools of the robotic arm 4. Also, a non-sterile person may be present to assist the remote operator 9 at the user console 2. When the procedure or surgery is complete, the system 1 and the user console 2 may be configured or set to a state to facilitate postoperative procedures such as cleaning or sterilization and input or printing of medical records via the user console 2.

[0022] In one aspect, the remote operator 9 provides an input command for driving (moving) one or more robot arm actuators 17 (or drive mechanisms) of the system 1 for remote operation by holding and moving the UID 14. The UID 14 can be communicatively coupled to the rest of the system 1, for example, via the console computer system 16 (or host). The UID 14 can generate a spatial state signal corresponding to the movement of the UID 14, for example, the position and orientation of the handheld housing of the UID, and the spatial state signal may be an input signal for controlling the movement of the robot arm actuator 17. The system 1 may control the proportional movement of the actuator 17 using a control signal derived from the spatial state signal. In one aspect, the console processor of the console computer system 16 receives the spatial state signal and generates a corresponding control signal. Based on these control signals, which control how the actuator 17 is energized to drive the segments or links of the arm 4, the movement of the corresponding surgical tool attached to the arm may mimic the movement of the UID 14. Similarly, an interaction between the remote operator 9 and the UID 14 can generate a gripping control signal for closing the jaws of the gripper of the surgical tool 7 to grip the tissue of the patient 6, for example.

[0023] System 1 may include several UIDs 14, in which case respective control signals are generated to control the actuator of each arm 4 and the surgical tool (end effector) for each UID. For example, the remote operator 9 may move the first UID 14 to control the movement of the actuator 17 within the left robotic arm, in which case the actuator responds by operating joints, gears, etc. within that arm 4. Similarly, movement of the second UID 14 by the remote operator 9 controls the movement of another actuator 17, which in turn drives other joints, gears, etc. of System 1. System 1 may include a right arm 4 on the right side of the patient fixed to the bed or table and a left arm 4 on the left side of the patient. The actuator 17 may include one or more motors, and the motors are controlled to drive the rotation of the joints of the arm 4 to change, for example, the orientation of the endoscope or gripper of the surgical tool 7 attached to that arm with respect to the patient. The movement of several actuators 17 within the same arm 4 may be controlled by a spatial state signal generated from a particular UID 14. The UID 14 may also control the movement of each surgical tool gripper. For example, each UID 14 may generate respective gripping signals for controlling the movement of an actuator, such as a linear actuator, that opens and closes the jaws of the gripper at the distal end of the surgical tool 7 for gripping tissue within the patient 6.

[0024] In some embodiments, the communication between the surgical robot table 5 and the user console 2 may be through the control tower 3, which may convert user commands received from the user console 2 (more specifically, from the console computer system 16) into robot control commands to be sent to the arm 4 on the surgical table 5. The control tower 3 may also send status and feedback from the surgical table 5 to the user console 2. The communication connections between the surgical table 5, the user console 2, and the control tower 3 may use any suitable one of various wireless data communication protocols, for example, the BLUETOOTH protocol, via wired (e.g., optical fiber) and / or wireless links. Any wired connection may optionally be built into the floor and / or wall or ceiling of the operating room. The system 1 may provide video output to one or more displays, including a display in the operating room and a remote display accessible via the Internet or other network. The video output or feed may also be encrypted to ensure privacy, and all or part of the video output may be stored on a server or an electronic medical record system.

[0025] FIG. 2 shows a depiction of an ultrasonic instrument 20 and a generator 25 according to one aspect of the present disclosure. As shown, the ultrasonic instrument is a hand-held laparoscopic tool configured to perform ultrasonic surgery (e.g., tissue cutting and sealing) based on manual operation of the instrument (e.g., the handle 21) by an operator (e.g., a surgeon). For example, during a laparoscopic (or endoscopic) surgical procedure, a small incision may be made in the patient, and the ultrasonic instrument may be inserted into the patient's cavity (e.g., gas may be used for cavity ventilation), and the end effector may be used by the operator to manipulate the tissue and perform surgery (e.g., cutting and / or cauterizing, etc.). The ultrasonic instrument is coupled (e.g., via a cable) to a generator (as shown) that enables the ultrasonic instrument to operate in one or more power states as described herein.

[0026] According to an aspect of the present technology, the ultrasonic instrument includes a handle (e.g., including a tool drive unit) 21, a shaft (or cannula) 22, and an end effector 23 that is loaded into the cannula (e.g., can be coupled to the shaft of the instrument).

[0027] The handle 21 is arranged to be held by an operator, enabling the operator to manipulate the ultrasonic instrument (e.g., its end effector 23) during a surgical procedure. In one embodiment, the handle may include one or more inputs (e.g., a trigger, one or more buttons, etc.) that enable the operator to control the ultrasonic instrument. For example, the instrument may include a trigger that generates a control signal that enables the user to control the end effector of the instrument (and / or control a part of the surgical system) when pulled by one or more fingers of the user while being gripped. In particular, the trigger may be arranged to operate the end effector (e.g., by adjusting the position of the hinged arm 31 shown in FIG. 3). In another aspect, the handle may include one or more inputs for changing the power state of the instrument. Further description regarding the power state of the instrument is described herein.

[0028] As described herein, the handle may include a tool drive unit arranged to drive the end effector 23 of the ultrasonic instrument. Specifically, the tool drive unit may include a (for example) linear motor or actuator arranged to vibrate (or oscillate) the end effector (blade) at one or more frequencies (for example, a very high (ultrasonic) frequency and a low frequency). In some embodiments, the tool drive unit is configured to vibrate the end effector such that a portion of the end effector (for example, the blade) moves back and forth along one or more axes. Specifically, the tool drive unit may vibrate the end effector over one or more ranges of motion, and over each range of motion, the end effector (blade) may be displaced by a different distance from the starting (or beginning) position. Further explanation of how the end effector vibrates is described herein. In another embodiment, the tool drive unit may include an ultrasonic transducer configured to vibrate the end effector in accordance with an input voltage / input current (applied, for example, by the generator 25).

[0029] As previously described, the ultrasonic instrument may include an end effector 23 and a handle 21 (including a tool drive unit). Specifically, the instrument includes a grip portion 21, a shaft 22 coupled to the distal end of the handle, and an end effector 23 coupled to the distal end of the shaft. In that case, the ultrasonic instrument referred to herein may be an end effector that can be coupled to the handle (for example, via the shaft 22 of the handle to the tool drive unit). In one embodiment, the end effector of the ultrasonic instrument, for example, may be separate from the handle and may be removably coupled to the handle. In some embodiments, the shaft receives and guides, for example, the blade (shaft) to couple to the instrument.

[0030] As described herein, the surgical system 1 includes an ultrasonic instrument 20 configured to generate heat based on the vibration of its end effector 23. In another embodiment, the instrument may be any type of energy (e.g., endoscopic, laparoscopic, etc.) tool designed to generate heat.

[0031] As previously described, the ultrasonic instrument 20 may be a handheld laparoscopic instrument that can be manually held and operated by an operator. In another embodiment, the instrument may be part of a surgical robot arm. Specifically, the ultrasonic instrument may be coupled to a robot arm and powered by a generator, as described herein. For example, the ultrasonic instrument may be coupled to the distal end of a robot arm (e.g., arm 4 of FIG. 1), and the robot arm includes several components that enable the robot arm to be controlled by an operator. For example, the surgical robot arm 4 may include a plurality of links and a plurality of actuation joint modules for actuating the plurality of links relative to each other. The joint modules may include various types such as pitch joints or roll joints, but these may substantially restrict the movement of adjacent links relative to others around a particular axis. The plurality of joint modules of the robot arm 4 may be actuated to position and orient the ultrasonic instrument for robotic surgery. In one embodiment, the ultrasonic instrument may be coupled to the distal end via a tool drive arranged to actuate the end effector 23 of the instrument.

[0032] When the ultrasonic instrument is coupled to a robot arm, the movement and operation of the ultrasonic instrument may be performed via one or more user control units (e.g., UID, foot pedal, etc.) coupled to the surgical system. For example, the UID may be arranged to open and close the gripper 23 of the ultrasonic instrument, and / or may be arranged to adjust the (spatial) spatial position of the gripper (in space) based on the position of the UID.

[0033] Referring to FIG. 3, this figure shows the end effector 23 of the ultrasonic instrument of FIG. 2. Specifically, this figure shows that the end effector is a gripping tool (or gripping device) including a blade (or tip) 30 as one jaw and a hinge arm (or jaw) 31 rotatably coupled to a joint (or robotic wrist) 32 coupled to the distal end of the shaft. In another aspect, the end effector 23 (e.g., the joint 32 of the end effector 23) may be a part of a part (distal end) of the shaft 22. In one aspect, the gripping tool (or a part of the gripping tool) is received through the shaft 22. For example, the blade may be received (and extend) through the shaft and is arranged to be coupled to a tool drive portion (e.g., of the handle 21) at or towards the proximal end of the shaft. Thus, as shown in the figure, the blade extends through the shaft (shown by the dashed line), and a part of the blade (e.g., the tip) extends out of the shaft 22 and into the environment. Inside the shaft, there are two buffer portions 33 arranged between a part of the blade extending through the shaft and the shaft (e.g., the inside of the shaft). In one aspect, the buffer portion may be designed to prevent the blade from contacting the inside of the shaft (e.g., while the blade is vibrating back and forth). In one aspect, the blade can (at least partially) contact (e.g., touch) the buffer portion during operation (while the blade is vibrating). In another aspect, the inner portion of the blade may not contact (at least one of) the buffer portions when the blade vibrates. In another aspect, the blade may accidentally contact at least one buffer portion. For example, during a surgical operation, an object contacts the shaft, shifting (or moving) the inner portion of the blade towards the buffer portion due to the impact of the object, causing the blade to contact the buffer portion. In another aspect, the shaft may not include the buffer portion. In another aspect, the blade 30 may be coupled to the shaft 22 (a part of it) (e.g., at the distal end of the shaft). Thus, the inner portion of the shaft shown by the dashed line may be coupled to the blade 30.

[0034] The hinge arm 31 is rotatably coupled to the shaft 22 (at the joint 32) and is arranged to rotate about the rotational (Z) axis (e.g., in the Z direction). Specifically, the gripping portion may be arranged to open and close based on the rotational position of the hinged arm about the axis of rotation of the joint relative to the blade (and / or shaft). For example, the gripper may be arranged to open (or be in the open position) when the hinged arm is rotated away from the blade (e.g., by a threshold distance). While in this position, the end effector may be oriented such that an object such as tissue can be disposed between the blade and the hinged arm (e.g., by moving the end effector around the object). The gripper may be closed (or be in the closed position) when the hinged arm rotates towards the blade (e.g., within a threshold distance), whereby the gripper may grip an object between the blade and the hinged arm. As described herein, the hinged arm may be arranged to apply pressure to the gripped object (e.g., compress the object between the jaws) to grasp the object and / or perform an incision on the object. In another aspect, the hinged arm 31 may be rotatably coupled to a portion of the blade. In one aspect, the blade 30 and the hinged arm may be received through a shaft such that the arm (and / or blade) is coupled to another shaft passing through the shaft 22.

[0035] As described herein, the blade 30 is the jaw of the gripper. In particular, the blade is a jaw that cannot rotate (e.g., about the Z-axis line) relative to the end effector. The blade may be arranged to vibrate along the longitudinal (Y) axis line (in the Y-axis line) of the blade to generate heat while the ultrasonic instrument is in a high-power state (or mode). In particular, the blade is driven to move back and forth (e.g., linearly) along the longitudinal axis line of the end effector (and through the cannula as described herein) so as to repeatedly displace the blade 30 at a (e.g., constant) frequency. Specifically, the blade may vibrate (e.g., reciprocate back and forth) over a range of motion (or displacement), in which case the blade moves a distance (e.g., forward or away from the end effector) from the starting position and then returns that distance. In one aspect, the range of motion may be the distance the blade moves from the starting position to the extended position. In another aspect, the range of motion may be the distance the blade moves back and forth.

[0036] As described herein, the blade may generate frictional heat while vibrating in contact with the object. Specifically, the blade may contact and vibrate against the tissue while the gripper is compressing the tissue between the two jaws 30 and 31. When the blade vibrates, the end effector may cut and / or cauterize the tissue as described herein. In one aspect, the blade may vibrate differently (e.g., over different ranges of motion) based on the power state of the ultrasonic instrument (e.g., how much power is being provided). Further explanation of the vibrating blade and power state of the ultrasonic instrument is described herein.

[0037] As described so far, the end effector 23 may be a gripper. In another aspect, the end effector may be any type of tool that is designed to be operated by an ultrasonic instrument (e.g., its handle 21). For example, the end effector may be an endoscope, a stapler, or the like.

[0038] Returning to FIG. 2, the generator 25 is configured to control (e.g., heat) the end effector 23 by controlling an ultrasonic instrument and providing power to the ultrasonic instrument while the instrument is coupled to and being used by an operator (e.g., during a laparoscopic surgery in which tissue is manipulated and / or one or more surgical tasks are performed on the tissue, such as cutting, sealing, and / or dissecting, grasping, and incising blood vessels and tissue). In particular, the generator may provide power to the ultrasonic instrument such that the surgical system 1 (e.g., its ultrasonic instrument) can operate in one of one or more power states. For example, the generator may provide power to the instrument such that the ultrasonic instrument is in a "high power" state (or "heating cycle"), in which state the instrument draws power (or current) from the generator (e.g., at a particular voltage) to generate heat in the end effector 23. For example, the generator may provide a (e.g., first) current (or input current) to the handle of the ultrasonic instrument (e.g., the tool drive of the handle), and the ultrasonic instrument may use this current to drive the blade 30 to vibrate (or oscillate) over a (first) range of motion (and at a particular frequency). Frictional heat may be generated by the end effector as the blade of the end effector vibrates over this range of motion while being pressed against an object such as tissue as described herein. In another aspect, the ultrasonic instrument may be arranged to operate in a "low power" state (or "cooling cycle"), in which case the ultrasonic instrument no longer draws the (sufficient or comparable) power provided by the generator to heat the end effector while the instrument was in the high power state. Specifically, while in this state, the generator may be configured to provide the ultrasonic instrument with less power than the power provided by the generator while the instrument was in the high power state such that the end effector does not generate heat (e.g., if in contact with an object). In particular, the generator may provide the ultrasonic instrument with less current (e.g., a second current) than the (first) current provided by the generator while the instrument was operating in the high power state, and as a result, this does not cause the end effector to generate heat (or as much heat as when the ultrasonic instrument was in the high power state).As a result, when the ultrasonic instrument transitions from a high-power state to a low-power state, it may begin to cool. Eventually, when maintained in the low-power state, the ultrasonic instrument will drop to (at least) a threshold temperature (e.g., room temperature). In one aspect, the second current may be less than a predefined threshold current. In one aspect, the blade may vibrate at the same frequency in the low-power state as in the high-power state. In another aspect, the blade may vibrate within an allowable frequency range.

[0039] As a result, due to the smaller current provided to the instrument while in the low-power state, the blade of the end effector can be driven by the tool drive 21 differently than when the instrument is in the high-power state. In particular, the blade may vibrate over a different range of motion than the range of motion over which the blade vibrates while the instrument is in the high-power state. For example, while in the high-power state, the blade may vibrate over a first (e.g., high) range of motion, which can cause heat to be generated in the blade when pressed against an object, while while in the low-power state, the blade may vibrate over a second (lower) range of motion that may be smaller than the first range of motion (e.g., the blade is displaced less along the longitudinal axis than the first range of motion). In some aspects, the second range of motion may be less than a minimum threshold (e.g., a threshold at which the blade generates heat if the blade vibrates beyond the minimum threshold). In one aspect, the end effector may not generate frictional heat while in contact with an object such as a blood vessel (e.g., while the gripping portion compresses the object) while vibrating over this lower range of motion. In one aspect, the resonant frequency is maintained within an allowable range regardless of the power state in which the instrument is operating.

[0040] In one aspect, the difference in the vibration of the end effector may be based on the amount of power drawn by the ultrasonic instrument while in different states. For example, the range of motion displaced while the blade is oscillating may be (e.g., proportional to) based on the power drawn by the instrument, such that more power drawn by the instrument may cause the blade to vibrate over a higher range of motion. Conversely, while the ultrasonic instrument is in a low-power state, the instrument may draw less power, causing the blade to vibrate less (than while the instrument is in a low-power state), resulting in less frictional heat being generated by the blade (e.g., while in contact with tissue). In another aspect, the blade may be in a low-power state and generate some frictional heat while in contact with the object, but less than the heat generated while the instrument is in a high-power state. In this case, this generated frictional heat may not be sufficient to cut and / or seal the tissue. In some aspects, as a result of operating in a low-power state, the end effector of the ultrasonic instrument may enter a cooling cycle, thereby dissipating the heat generated by the end effector while the instrument was in a high-power state (e.g., over a period of time). In another aspect, the blade may not vibrate while in this low-power state (e.g., the tool drive may not drive the blade).

[0041] In one aspect, the system may enter (or operate in) at least one of the power states based on a user input (e.g., received by generator 25). In particular, the generator may provide power to the ultrasonic instrument based on receiving a user input to one or more input devices (e.g., an input to a foot pedal, a UID controlled by an operator and communicatively coupled to system 1, and / or an input at handle 21 of the ultrasonic instrument). The power provided based on the user input may put the ultrasonic instrument in a high power state where the ultrasonic instrument draws power from the generator to heat an end effector 23 (e.g., blade 30 of end effector 23). For example, when the generator receives a (first) user input (e.g., by an operator pulling or pushing a trigger on handle 21), the generator may provide current to the ultrasonic instrument (e.g., the tool drive of the ultrasonic instrument), and the ultrasonic instrument may use the current to drive the end effector as described herein. Thus, when the trigger controls a hinged arm of the end effector, the generator is configured to provide current when the hinged arm is moved (e.g., towards blade 30 by at least a threshold distance). In another aspect, the system may enter a low power state based on another (e.g., second) user input (e.g., receiving an input from a different input device coupled to the generator such as a foot pedal).

[0042] In some embodiments, the ultrasonic instrument may be arranged to switch between a high-power state and a low-power state. As described herein, the instrument may operate in the high-power state while the generator is receiving a user input (e.g., the user pulls or presses a trigger on the handle). The instrument may operate in the low-power state in response to the generator not receiving a user input. For example, the ultrasonic instrument may switch from the high-power state to the low-power state in response to the user releasing a trigger on the handle, and the generator may transition between the two states). In one embodiment, as described herein, the instrument may operate in the low-power state while the operator is not actively using the instrument to perform an ultrasonic instrument operation. Specifically, the system may enter the low-power state, but no user input to one or more input devices used by the operator to enter the high-power state is received. However, if the operator desires to actively use the ultrasonic instrument, the ultrasonic instrument may switch back to the high-power state (e.g., in response to a user input). In another embodiment, the instrument may operate in the low-power state in response to receiving a user input (e.g., the user presses a button on the UID). In another embodiment, the instrument may operate in this state for a period of time. As described herein, the surgical system is configured to determine the temperature of the end effector while in the low-power state (e.g., after switching from the high-power state) to notify the operator of a temperature that may increase because the instrument is operating in the high-power state. If the end effector is cooled to a particular temperature (e.g., below a predefined temperature), at this temperature, since the end effector may not cause thermal damage when in contact with tissue, the generator may stop the instrument by ceasing to provide a lower current.

[0043] In one aspect, the generator may provide different levels of current to heat the blade, which may be based on user input. For example, the generator may receive a first user input (e.g., from one petal coupled to the generator) and, in response, provide the ultrasonic instrument with the maximum (allowable) amount of current. Next, the ultrasonic instrument may drive the end effector over the maximum (e.g., predefined) range of motion, which may result in the end effector generating heat at a (first) high temperature. However, when the generator receives a second user input (e.g., from another petal coupled to the generator), the generator may provide the ultrasonic instrument with a lesser amount of current. As a result, the ultrasonic instrument may draw less power and vibrate the end effector over a (second) lower range of motion that may be lower than the first range of motion in which the blade vibrates in response to the first user input. However, this lower range of motion may heat the end effector at a temperature lower than the first temperature of the end effector when the ultrasonic instrument draws more current (in response to the generator receiving the first user input). By heating the end effector to different temperatures, different types of tissue may be cut and / or cauterized. For example, to cut and / or cauterize tissue, more fatty tissue may require the end effector to be at a higher temperature (having the first temperature), while thinner (and less fatty) tissue may require less heat (having the second temperature). In another aspect, the generator may be configured to provide one type of current while in a high-power state (e.g., driving the end effector over a first high range of motion).

[0044] As described herein, the ultrasonic instrument may be activated (e.g., operate in a high-power state) based on whether the end effector is in a closed position to grip an object (e.g., a portion of tissue). For example, the ultrasonic instrument may be activated (e.g., by a user) such that the ultrasonic instrument can operate in a high-power state to draw a current sufficient to generate heat in the end effector. In particular, the generator may activate the ultrasonic instrument when it receives a user input to close the end effector (e.g., move the hinged arm 31 within the distance of the blade 30). When a user input for moving the hinged arm is received, the generator may be configured to provide (e.g., sufficient) power to activate the instrument as described herein. In some aspects, the generator may activate the instrument based on a determination that the hinged arm and / or blade is in contact with an object. For example, the ultrasonic instrument may include one or more sensors (e.g., force / pressure sensors) that detect the presence of the object and / or detect that the object is in contact with both arms. In particular, the generator may enter a high-power state when it is determined that the gripper is compressing the object (based on the pressure detected by the sensor exceeding a threshold). When this decision is made, the generator may provide a first current to oscillate the blade to generate heat in the blade. When the pressure reading drops below the threshold (which means the object has been released by the gripper), the generator may switch to a low-power state.

[0045] In one aspect, a surgical system (e.g., its generator) may be configured to determine one or more characteristics of an ultrasonic instrument (of its end effector) while the instrument is in one or more power states. For example, the generator may be configured to track (or monitor) characteristics such as input voltage, input current, resonance state, resonance frequency, and / or (e.g., mechanical) impedance of the ultrasonic instrument (of its end effector). In one aspect, the generator may be configured to monitor at least some of these characteristics of the instrument while the instrument is operating in a high-power state. Note that the system may be configured to determine (at least some of) these characteristics while the instrument is in a low-power state (cooling cycle or cooling period) due to the instrument drawing at least some power. For example, the generator may determine the resonance frequency and impedance of the end effector (e.g., blade 30 of the end effector) while in the low-power state. Further determination of these characteristics is described herein.

[0046] In one aspect, the surgical system may include additional components. For example, the system may include a cable that connects the generator to an ultrasonic instrument (e.g., an ultrasonic transducer configured to convert an electrical drive signal into mechanical vibrations). In one aspect, the ultrasonic transducer may be connected to a waveguide that is connected to blade 30 of end effector 23.

[0047] Also as shown, generator 25 includes a display 24 that is arranged to display information regarding the operation of the ultrasonic instrument. For example, the display may present temperature information, what state the ultrasonic instrument is currently in, and one or more of the characteristics described herein.

[0048] FIG. 4 is a block diagram of a surgical system 1 according to one aspect. The system includes an ultrasonic instrument 20, a generator 25, a controller 40, a storage device 44, a display 15, and a speaker 43 (which may be part of an electronic device of the system such as a stand-alone speaker or a user console 2). In one aspect, the system may include more or fewer elements, such as having two or more displays and / or not having a speaker.

[0049] Examples of storage devices (e.g., non-transitory machine-readable storage media) may include read-only memory, random access memory, CD-ROM, DVD, magnetic tape, optical data storage devices, flash memory devices, and phase change memory. Although shown as separate from the controller 40, the storage device may be part of the controller (e.g., internal memory of the controller).

[0050] In some aspects, controller 40 may be a dedicated processor such as an application specific integrated circuit (ASIC), a general purpose microprocessor, a field programmable gate array (FPGA), a digital signal controller, or a set of hardware logic structures (e.g., filters, arithmetic logic units, and dedicated state machines). In one aspect, the controller may be part of an electronic device such as console computer system 16, control tower 3, and / or user console 2. Although illustrated as a single component, in one aspect, the controller may include one or more electronic components (e.g., a processor, memory, etc.) communicatively coupled across the above devices (e.g., communicating via a wireless computer network) on a single electronic device (such as console computer 16). In some aspects, the controller may be part of a separate device, such as part of a remote server communicating with one or more electronic devices. In another aspect, the controller may be part of generator 25 (e.g., may be at least partially integrated within generator 25). In that case, at least some of the other elements (e.g., speakers and displays) may also be part of the generator (may be integrated within the generator). As a result, at least some of the operations performed by the controller described herein may be performed by the generator.

[0051] In one aspect, the controller is configured to perform a temperature estimation operation of the surgical system 1 to determine (e.g., in real time) the temperature (e.g., of the end effector of the ultrasonic instrument) while the instrument is in one or more power states (e.g., a low power state in which the blade of the end effector is not actively heated to cut and / or seal tissue). Specifically, the controller may determine the temperature based on one or more characteristics of the ultrasonic instrument determined while the instrument is in a low power state, such as the resonant frequency of the end effector (e.g., its blade). The controller may use one or more (predetermined) models (e.g., which may be stored in the storage device 44) of temperature to determine the temperature, whereby the temperature model (e.g., a polynomial model for the cooling period) may output the estimated temperature of the blade as an input based on the resonant frequency (in response). For example, the controller may determine a normalized change in the resonant frequency (e.g., based on the difference between a (predetermined) baseline resonant frequency and the current resonant frequency reading), and determine one or more model coefficients (based on the resonant frequency at the start of the cooling period and a predetermined constant). The controller may estimate the temperature by applying the normalized resonant frequency change and the coefficients as inputs to the model, and the model generates the temperature estimate as an output.

[0052] In one aspect, the controller may be configured to use one or more (predetermined) models to determine the temperature of the end effector while the instrument is in either a heating cycle or a cooling cycle. For example, the controller may be configured to estimate the temperature of the end effector by applying a change in the resonant frequency (e.g., the difference between a baseline (or previously determined) resonant frequency and the current resonant frequency of the end effector) to a hysteresis model (stored in the storage device 44) that includes a hysteresis relationship between the change in the resonant frequency of the end effector and the corresponding temperature of the end effector. In another aspect, the controller may use any method to determine the temperature of the end effector while the ultrasonic instrument is operating in one or more power states.

[0053] In one aspect, (at least some of) the operations of the temperature estimation operation may be performed by the controller while the end effector is in a cooling period (e.g., while the instrument is in a low power state). In addition to (or instead of) being performed during the cooling period, the temperature estimation operation may be performed while the end effector is "in the air", which means that the blade is not (at least partially) immersed in a liquid and / or is not in contact with an object such as tissue. In particular, as described herein, during laparoscopic surgery, one or more gases may be used to create a cavity within the patient's abdomen. In that case, the temperature estimation operation may be performed while the end effector (blade) is within the cavity but not in contact with tissue and / or liquid. In one aspect, the model used by the controller to estimate temperature may be pre-defined in a controlled environment (e.g., a laboratory) while the blade is in the air during a surgical procedure (e.g., within the patient cavity but not in contact with an object and not immersed in a liquid).

[0054] When the blade is in contact with an object and / or is at least partially immersed in a liquid, in either case, the model may not be valid (or inaccurate) in predicting (estimating) the temperature of the blade due to a change in the characteristics of the blade, such as the resonant frequency of the blade. For example, when the blade is in contact with an object, due to an increase in the stiffness k of the blade, its resonant frequency (or damped natural frequency, ω d ) increases. In particular, the damped natural frequency can be seen as follows.

[0055]

Equation

[0056] Here, γ is the damping ratio, ω n is the undamped natural vibration frequency of the blade and can be written as follows depending on the stiffness of the blade.

[0057]

Number

[0058] Here, m is the mass of the blade. In one aspect, m may include the mass of the blade and any object (e.g., residual tissue) attached to the blade. The attenuation ratio can be written as follows.

[0059]

Number

[0060] Here, b is the attenuation on the blade. Thus, when k increases, ω n increases, and thus γ decreases, both resulting in an increase in ω d .

[0061] Conversely, when the blade is at least partially immersed (submerged) in a liquid (e.g., not touching an object such as tissue), ω d can decrease as a result of an increase in the attenuation b, due to an increase in the attenuation ratio γ. However, when the blade is immersed in a liquid and touching an object, ω d may also change due to an increase in k and a decrease in b. Thus, due to changes in the resonance frequency resulting from touching and / or being immersed in an object, the controller may not be able to accurately estimate the temperature using a model-based method. As a result, the controller may determine the state of the end effector of the instrument (e.g., whether it is touching an object and / or is immersed in a liquid), and in response, may be configured to determine (or estimate) the (new) temperature of the end effector based on that determination. Further explanation regarding estimating the temperature is described herein.

[0062] In one aspect, at least some of the operations performed by the controller may be stored in a memory of the surgical system (e.g., a storage device and / or (internal) memory of the controller) and implemented by software (e.g., as instructions) executed by the controller and / or implemented by a hardware logic structure. In one aspect, at least some of the operations performed by the controller may be performed each time the instrument enters a low-power state (or switches between two or more power states, such as switching from a high-power state to a low-power state).

[0063] As shown, the generator may receive user input (e.g., via one or more electronic devices coupled to the generator) to cause the generator to perform one or more operations. For example, the user input may be received via the ultrasonic instrument (e.g., when the user pulls the trigger of the handle) to cause the generator to provide a current that switches the ultrasonic instrument from a low-power state to a high-power state, as described herein.

[0064] FIG. 5 is a flowchart of a process 50 for determining the state of an end effector, such as whether the end effector 23 of the ultrasonic instrument 20 is at least partially (immersed) in a liquid and / or in contact with a target (e.g., tissue). In particular, at least some of these operations may be performed while the ultrasonic instrument is in one of the one or more power states described herein, e.g., a low power state, once and / or multiple times. For example, as described herein, at least some operations may be performed when the ultrasonic instrument switches from a high power state to a low power state (e.g., each time), which may also be based on user input. In that case, the surgical system may perform these operations to determine the state of the end effector, such as whether the end effector is in contact with the target and / or immersed in a liquid. In some aspects, at least some of the operations may be periodically performed while in a low power state to determine the state of the end effector when the end effector is in a cooling cycle. In one aspect, the process may be performed by the surgical system 1. For example, each of the processes may be performed by the controller 40. As another example, at least some of the operations may be performed by the generator 25 (e.g., by one or more of its processors). Accordingly, this figure is described with reference to FIG. 4.

[0065] The process is such that the controller 40 determines the baseline (or initial) impedance Imp of the end effector (blade) of the ultrasonic instrument Baselineis started by determining (block 51). As described herein, the impedance may be a mechanical impedance that can be determined by a controller using one or more of the (monitored) characteristics of the ultrasonic instrument. For example, the controller may determine the input current of the ultrasonic instrument (e.g., used to drive the blade of the end effector) and determine the mechanical impedance based on these parameters (e.g., based on Ohm's law). In one aspect, the input voltage may vary to maintain a current that is set to compensate for changes in impedance. In one aspect, the controller may determine the impedance by applying one or more of the characteristics to a (predetermined) impedance model (e.g., an electromechanical model of the blade impedance) that outputs the mechanical impedance. In another aspect, the controller may use any well-known method to determine the impedance of the blade. In one aspect, the baseline impedance may be determined at an initial time t0, such as when the ultrasonic instrument 20 is coupled (e.g., plugged in) to the generator 25. For example, when the instrument is plugged into the generator, the controller may determine Imp Baseline One or more diagnostic operations may be performed on the instrument to determine. In another aspect, the generator may be configured to determine Imp Baseline . Thus, based on the operation, the generator may determine the baseline impedance of the blade of the end effector and provide that impedance to the controller.

[0066] In some embodiments, this baseline impedance may be determined while the end effector is at room temperature (or near room temperature), e.g., between 20-25° C., and / or while the end effector is in air, e.g., while the blades of the end effector are not in contact with an object. In another embodiment, the baseline impedance may be determined once and stored in the storage device 44 (or the memory of the controller 40) of the surgical system 1. For example, the baseline impedance may be determined when the instrument is first coupled to the generator. In another embodiment, the baseline impedance may be determined each time the ultrasonic instrument is plugged into the generator. In another embodiment, the baseline impedance may be determined at the start of the surgical system (e.g., during initial power-up), e.g., the ultrasonic instrument of the surgical system. In another embodiment, the baseline impedance may be an impedance determined previously (e.g., during a previous implementation of process 50).

[0067] In one embodiment, the baseline impedance Imp Baseline is determined to be the impedance level of the end effector when the ultrasonic instrument is in a low power state, the end effector is in an open position, and / or the ultrasonic instrument (e.g., the end effector and the shaft of the ultrasonic instrument) is not in contact with any object. In another embodiment, the baseline impedance may be determined (e.g., each time) when the ultrasonic instrument enters a cooling period. In some embodiments, Imp Baseline may vary between different devices. Further, Imp BaselineAfter activation repeated throughout the surgical procedure (switching repeated between a heating cycle and a cooling cycle), it may drift or step down / step up. Since ΔImp, which is a change in impedance (from the baseline impedance level), is what the controller uses to detect whether the end effector is in contact with the object, the controller may be configured to periodically update the baseline impedance value to prevent false object contact detection due to impedance drift or changes due to repeated activation.

[0068] The controller 40 determines Imp, which is the impedance of the end effector (at block 52). For example, the impedance may be the "current" impedance determined by the controller during the surgical procedure (while the instrument is being used by the operator and is in the cooling cycle). In one aspect, the controller may determine Imp using the same (or the same) operation as that used to determine the baseline impedance. In some aspects, the impedance determined at this point may be determined after the baseline impedance. The controller determines the impedance change ΔImp based on a comparison between the baseline impedance and the determined impedance (block 53). In particular, the impedance change may be the difference between the two impedances, where ΔImp = Imp - Imp Baseline is.

[0069] The controller 40 determines the baseline resonance frequency of the end effector (e.g., the blade) of the ultrasonic instrument (block 54). For example, the controller may determine the baseline resonance RF of the blade at t0 as described for the baseline impedance. In one aspect, the controller may determine RF Baseline at the same time as (or simultaneously with) Imp Baseline is determined. Baselinemay be determined (at least in part). Thus, RF Baseline may be determined under conditions similar to Imp Baseline , such as when the instrument is plugged into the generator, determined at room temperature, etc.).

[0070] In some embodiments, the generator electronically determines the resonant frequency. For example, the generator may detect the voltage and current waveforms (and the phase angle difference between the two waveforms) used to drive the blades of the end effector. Specifically, the ultrasonic instrument 20 (e.g., the tool drive unit) may include an ultrasonic transducer configured to vibrate the blade according to the input voltage and current waveforms. The frequency that generates a phase angle difference of a threshold value (e.g., zero) is the resonant frequency. In one embodiment, the generator may continue to drive the ultrasonic transducer in a resonant state and adjust the output voltage (sometimes referred to as phase locking) to continue to drive in a resonant state (since the resonant frequency changes with temperature changes). In another embodiment, the controller 40 may adjust the output frequency. In another embodiment, other well-known methods may be used to determine the resonant frequency.

[0071] In one embodiment, the (at least some of the) operations performed in block 51 and / or block 54 can be omitted from process 50. For example, as described herein, at least some of these operations may be performed each time the ultrasonic instrument enters a low power state. However, the determination of the baseline impedance and / or the baseline frequency may, in some embodiments, be performed only once (e.g., at initial power-on). As a result, process 50 may omit any (or both) of these operations in subsequent (at least partial) implementations of this process. Thus, block 51 and block 54 may be optional (as shown, for example, as boxes with dashed boundaries).

[0072] The controller 40 is configured to determine the (or, current) resonance frequency RF of the end effector (block 55). Specifically, the controller may determine RF in the same manner as the baseline resonance frequency, although RF may be determined after the baseline with respect to Imp Baseline in a manner similar to Imp. In one aspect, the controller may be configured to determine the impedance (at block 52) and / or the resonance frequency (at block 55) based on the configuration of the ultrasonic instrument. For example, these characteristics may be determined by (or in response to) the surgical system when the end effector of the instrument is in the open position (e.g., when operating even in a low power state). In another aspect, the characteristics may be determined after (or immediately after or within that time) the controller determines that the end effector is in the open position. In another aspect, the controller may determine any of these characteristics when the ultrasonic instrument switches between states, and / or may periodically determine the characteristics after entering a state. The controller determines a resonance frequency change ΔRF based on a comparison of the baseline resonance frequency and the determined resonance frequency (block 56). Specifically, the controller may determine the change based on the difference between the frequencies such that ΔRF = RF - RF Baseline The difference may represent a resonance frequency drift (or change therebetween) from the baseline (or nominal) resonance frequency of the blade to the determined resonance frequency.

[0073] The controller 40 determines that the impedance change ΔImp is the impedance liquid threshold Th Imp(Liquid)Determine whether it is greater than (and / or equal to) (determination block 57). In one aspect, at least partial immersion of the ultrasonic instrument (end effector) can result in an increase in mechanical impedance Imp (and thus can result in an increase in ΔImp). In particular, when the ultrasonic instrument is in a low power state where the current to the instrument is controlled (e.g., set to a predetermined value), the voltage may change due to immersion in order to maintain a specific current. As a result, when the end effector is at least partially immersed in the liquid when the mechanical impedance is determined (e.g., in block 52), the change in voltage may result in an increase in the determined impedance. In one aspect, Th Imp(Liquid) may be a predetermined threshold value (e.g., a threshold value determined in a controlled environment).

[0074] When ΔImp < Th Imp(liquid) i.e., when it means that the end effector (e.g., blade 30 of the end effector) is not at least partially immersed (e.g., no part of the blade is immersed in the liquid), the controller 40 determines whether the impedance change is greater than the threshold Th of the impedance object Imp(Object) (block 63). In particular, during a surgical procedure, the controller determines whether at least a part of the end effector is in contact with an object such as tissue, vein, etc. based on whether ΔImp < Th Imp(Object) . In one aspect, Th Imp(Object) may be a threshold value greater than Th Imp(liquid) . In another aspect, Th Imp(Object) is Th Imp(liquid)It may also be a smaller threshold value. In such a case, the controller presents a notification indicating that the end effector is in contact with the object (block 64). For example, the system 1 may display a pop-up notification indicating that the operator (e.g., the ultrasonic instrument used by the operator) is in contact with the object on the display 15. As another example, the controller 40 may output an audible notification through one or more speakers (e.g., speaker 43). For example, the audible notification may be one or more sounds (e.g., beep sounds) indicating that the end effector is in contact with the object. In another aspect, the notification may be spoken words (e.g., "The Blade is in Contact with an Object!"). In another aspect, any kind of notification may be presented.

[0075] Returning to decision block 57, when ΔImp>Th Imp(liquid) if so, the controller determines whether the resonance frequency change ΔRF is less than (and / or equal to) the resonance frequency threshold TH RF (decision block 58). Specifically, the controller may determine whether ΔRF<Th RF . During (at least partial) immersion of the end effector in the liquid, the impedance of the instrument may increase, but the resonance frequency of the end effector may decrease. In one aspect, the controller determines that the end effector is immersed in (or in contact with) the liquid based on the increase in impedance (e.g., ΔImp>Th Imp(liquid) ) and the decrease in resonance frequency (e.g., ΔRF<Th RF ) during the (same) period (e.g., the period during which both characteristics are monitored by the generator). Thus, when these changes occur (e.g., simultaneously, or contemporaneously within a certain period), it may be determined that the end effector is in contact with or immersed in the liquid.

[0076] ΔRF<Th RFIn the case of, the controller determines the threshold Th Imp(Object) ’ of the object with the new impedance (block 59). In one aspect, the threshold of the new object may be greater than the threshold of the object in decision block 63, such as Th Imp(Object) ’ > Th Imp(Object) . In one aspect, the controller is determining a new threshold value that is used when determining whether an end effector that is at least partially immersed in a liquid is also in contact with an object (for example, during a surgical procedure, the end effector may be grasping tissue immersed in saline). The controller may make this determination based on a change in impedance. In one aspect, the controller may increase the threshold of the impedance object based on the threshold liquid impedance. For example, the controller may increase the threshold by (at least) the liquid threshold such that Th Imp(Object) ’ = Th Imp(Object) + Th Imp(Liquid) . In another aspect, the new threshold impedance may be determined by increasing Th Imp(Object) by a predetermined amount.

[0077] The controller 40 determines whether the change in impedance is greater than the threshold Th Imp(Object)Determine whether it is greater than '

[0078] Some aspects may implement one or more variations to the process 50 described herein. For example, certain operations of the process may not be performed in the exact order illustrated and described. Certain operations may not be performed in one continuous series of operations, and different specific operations may be performed in different aspects. As described herein, the controller may perform at least some of the operations of this process to determine whether the end effector is immersed in a liquid and / or in contact with an object. In some aspects, the controller may determine, based on the operations performed, that the end effector is not immersed in a liquid and / or not in contact with an object. For example, in response to the resonance frequency change being greater than Th RF the controller may determine that the end effector is not (at least partially) immersed in a liquid.

[0079] In one aspect, at least some of the operations described herein may be performed simultaneously. For example, the controller may (at least partially) simultaneously determine whether the impedance change (at block 57) is greater than Th Imp(Liquid) and determine whether the resonance frequency change is less than Th RF In that case, the controller may determine that the end effector is not immersed in the liquid in response to at least one of the characteristics not meeting the conditions described herein.

[0080] In one aspect, the controller 40 may be configured to determine the type of liquid in which the end effector is at least partially immersed based on one or more of the characteristics of the ultrasonic instrument (e.g., impedance and / or resonance frequency). For example, blood may be more viscous than saline, and as a result, Imp when the end effector is immersed in blood may be greater than Imp when the end effector is immersed in saline. Thus, the controller may determine the type of liquid by comparing Imp and / or ΔImp to a threshold. For example, the controller may perform a table lookup into a (predetermined) data structure that associates the impedance (range) with the type of liquid using Imp. The controller may determine the type of liquid having an impedance similar or identical to the associated impedance of Imp. In one aspect, the presented notification may indicate the type of liquid (e.g., indicate that the end effector is immersed in blood).

[0081] FIG. 6 shows the operations performed by the end effector of the ultrasonic instrument and displays notifications based on whether the end effector is immersed in a liquid and / or in contact with an object. Specifically, each of the three stages 70-72 shows the display 15 (and / or the display 24 of the generator 25), and the display 15 shows an endoscopic video 73 showing the end effector 23 and a portion of the object 77 (e.g., tissue such as a blood vessel) immersed in the liquid 74. In one aspect, the display showing the endoscopic video may be a different display of the surgical system, such as the display 24 of the generator 25. In some aspects, the display may show other content, such as a graphical user interface (GUI) of the surgical system that displays other video content (e.g., related to the surgical procedure being performed by the operator of the system) and / or one or more UI items.

[0082] The first stage 70 shows the end effector 23 in front of the liquid 74 and the tissue 77. In one aspect, the end effector may be in air (e.g., within the patient's cavity during a surgical procedure). In one aspect, the end effector may be in a low power state where the end effector is hot but in a cooling cycle (e.g., cooling). In one aspect, at this stage, the controller may determine a baseline impedance and / or a baseline resonance frequency.

[0083] The second stage 71 indicates that the end effector 23 (a portion of the blade 30 thereof) enters (moves forward) into the liquid 74 and is partially immersed. In this case, the controller may determine that the end effector is in the liquid based on a change in one or more characteristics of the ultrasonic instrument. For example, as described herein, when the blade 30 of the end effector enters the liquid, the measured impedance of the blade may increase, and the measured resonant frequency of the blade may decrease. As a result, the controller may determine that the blade is immersed in the liquid 74. Note that this stage, in response to the controller's determination that the end effector is in the liquid, may display a notification 75 reading "End Effector Immersed in Liquid" on the display 15 (e.g., superimposed on the endoscope video 73) to warn the operator of the state of the end effector that may be out of the operator's field of view.

[0084] The third stage 72 indicates that the blade 30 of the end effector 23 has moved further forward (from the state shown in the second stage 71), where it is touching the tissue 77 while being immersed in the liquid 74. In particular, the controller makes this determination based on additional changes in characteristics such as the impedance of the end effector. This stage also indicates that the display 15 shows a notification 76 indicating that the end effector is immersed in the liquid and in contact with the object by including the text "End Effector Immersed in Liquid and in Contact with Object" to warn the operator of the state of the instrument.

[0085] Thus, this figure shows how the controller can continuously perform at least some of the operations of the process 50 shown in FIG. 5 to continuously monitor and update the operator on the state of the device.

[0086] As described herein, a surgical system may be configured to determine (estimate) and present (e.g., display on display 15) the temperature of an end effector (e.g., its blade) based on one or more of the monitored characteristics of an ultrasonic instrument, such as the resonant frequency, while the instrument is in one of its power states (e.g., low power state). Specifically, system 1 (controller 40 thereof) may estimate the temperature according to at least one temperature model configured to determine the temperature of the end effector in air. For example, the temperature model may estimate the temperature based on the resonant frequency of the vibrating blade of the end effector while the instrument is in the low power state. When the blade touches an object and / or is immersed in a liquid, the resonant frequency may be adversely affected (e.g., as described herein, the resonant frequency may increase while the blade is touching an object due to an increase in the stiffness k of the blade. As a result, the temperature model may not be able to effectively estimate the temperature of the blade. Thus, the system may be configured to estimate the temperature of the end effector based on the state of the instrument (e.g., whether the instrument is touching an object and / or is immersed in a liquid).

[0087] FIG. 7 is a flowchart of a process 80 for estimating the temperature of an end effector based on detection that an ultrasonic instrument is at least partially immersed in a liquid. Specifically, the operations may be performed by the controller 40 (and / or generator 25) of the surgical system 1. Process 80 begins with the controller 40 estimating (and displaying on a display such as display 15 of FIG. 4) the temperature of the end effector of the ultrasonic instrument (block 81). Specifically, the controller may determine one or more characteristics of the instrument, such as the resonant frequency of the end effector, and then apply the frequency to a predetermined temperature model, which outputs an estimated temperature value of the end effector. In one aspect, the temperature estimation may be performed while the instrument is in air (e.g., not touching an object and / or not immersed in a liquid). In some aspects, the temperature estimate may be determined while the instrument is in a cooling cycle (e.g., a low power state).

[0088] The controller 40 determines one or more characteristics of an end of the ultrasonic instrument (block 82). Specifically, the controller may determine the impedance and / or resonant frequency (e.g., from the generator) as described herein. The controller determines that the end effector is at least partially immersed in the liquid based on the one or more characteristics determined (e.g., in block 83). For example, the controller may determine that the blade of the end effector is immersed in the liquid in response to determining that the change in impedance ΔImp is greater than the impedance liquid threshold Th Imp(Liquid) as described in FIG. 5, and / or in response to determining that the change in resonant frequency ΔRF is less than the threshold Th RF as described in FIG. 5. In response to determining that the end effector is at least partially immersed in the liquid, the controller displays a notification indicating that the end effector is at least partially immersed in the liquid on the display of the surgical system (block 84). For example, the system may display a notification such as notification 75 of FIG. 6.

[0089] Based on the end effector being at least partially immersed in the liquid, the controller estimates (and displays) a new temperature of the end effector of the ultrasonic instrument (block 85). Specifically, the controller may replace the estimated temperature displayed on the system's display (as described in block 81) with the new temperature estimate. In one aspect, the new temperature estimate may be a temperature associated with the liquid in which the end effector is immersed. In particular, when the blade is immersed in the liquid, any residual heat of the blade is rapidly dissipated into the liquid. This is because most liquids have a high heat capacity compared to air. As a result, the blade is cooled (within a certain time) and reaches thermal equilibrium with the liquid such that the temperature of the blade becomes (almost) the same as the temperature of the liquid. Thus, in response to determining that the end effector is at least partially immersed in the liquid, the controller may estimate the temperature of the end effector to be the temperature of the liquid.

[0090] In one aspect, the controller may estimate a new temperature based on the determination of the liquid. For example, as described herein, the controller may be configured to determine the type of liquid in which the end effector is immersed (e.g., based on a change in the resonant frequency of the end effector). In that case, the controller may be configured to determine a new temperature based on the determination of the type of liquid in which the end effector is immersed. For example, the controller may perform a table lookup into a data structure that associates the type of liquid with a temperature. In another aspect, the controller may determine the temperature of the liquid by other means. For example, the surgical system may include a temperature sensor configured to detect the temperature of the liquid. In another aspect, the temperature of the liquid e may be a predetermined liquid (e.g., across one or more types of liquids).

[0091] Some aspects may implement variations to process 80 described herein. For example, at least some of the specific operations of the process may not be performed in the exact order illustrated and described. Specific operations may not be performed in one continuous series of operations, and different specific operations may be performed in different manners. For example, the operations within the dashed box may be optional operations that may not be performed while each process is being carried out. In another aspect, one or more operations (with or without a dashed box) may be optional. In one aspect, at least some of the operations described herein (e.g., performed in one or more of the processes described herein) may be performed automatically (e.g., without user intervention). As described herein, the operations of process 80 determine whether the end effector is at least partially immersed, and accordingly are used to estimate a new temperature. In some aspects, at least some of these operations may be performed based on whether the end effector is in contact with the object. For example, instead of (or in addition to) determining whether the end effector is immersed, the controller may determine whether the end effector is in contact with the object based on one or more characteristics of the end effector (e.g., impedance) (e.g., block 83). In response to determining that the end effector is touching the object, the controller may be configured to display a notification and estimate (and display) a new temperature of the end effector based on the end effector being in contact with the object (e.g., in the notification). In this case, the controller may be configured to estimate the temperature of the end effector to be the temperature of the object that the end effector is touching (e.g., about).

[0092] In another aspect, the controller may estimate the temperature of the end effector in contact with the object based on the amount of time the end effector has been in contact with the object. For example, when the end effector is in contact with the object, the temperature may change at a predetermined (e.g., linear) rate of change. In that case, the controller may estimate the temperature based on a predetermined rate and the time the end effector is in contact with the object. In one aspect, the controller may continuously update the displayed new temperature based on the length of contact between the end effector and the object. In another aspect, the controller may determine the temperature based on a temperature (linear) model that linearly adjusts the temperature based on an estimated value of the temperature (before contacting the object). In some aspects, when the end effector is determined to be immersed in a liquid and in contact with the object, the controller may estimate the new temperature of the end effector to be the temperature of the liquid. In some aspects, when the blade is immersed in a liquid, the temperature of the blade may be estimated to be the temperature of the liquid regardless of whether the blade is in contact with the object.

[0093] As described herein, the controller may estimate and display the temperature of the end effector. In one aspect, the temperature of the end effector (or the display of the temperature) may be displayed as a separate notification (or as the same notification) from a notification indicating that the end effector is immersed in a liquid (and / or in contact with the object). In another aspect, the notification of the state of the end effector may be based on the temperature. For example, when it is determined that the end effector is in contact with the object, the controller may be configured to determine whether an estimated value of the temperature of the end effector (e.g., in air and before contacting the object) exceeds a threshold. If so, the displayed notification may warn the operator that the end effector is too hot to touch the object.

[0094] In some embodiments, the controller may be configured to estimate the temperature of the end effector using one or more of the memory models described herein in response to determining that the end effector is no longer (at least partially) immersed in the liquid (and / or not in contact with the object). For example, the controller may be configured to monitor one or more characteristics of the end effector to determine whether the end effector is no longer immersed. For example, when it is determined that the change in impedance is less than the impedance liquid threshold and / or when it is determined that the change in resonant frequency is greater than the resonant frequency threshold, the controller may determine that the end effector is no longer immersed (e.g., in air). In response, the controller may be configured to estimate and display the temperature of the end effector using one or more of the models described herein and / or remove the displayed notification indicating that the end effector is immersed.

[0095] In some embodiments, the controller may continuously (or within a period) monitor the impedance level Imp (e.g., determine the level of impedance one or more times over a period) to prevent false triggering of object contact due to shift, thereby (e.g., in real time) updating Imp. Baseline Specifically, to update the baseline impedance, the controller may be configured to determine one or more impedances of the end effector over a period and may be configured to determine whether the change in impedance over the one or more impedances over the entire period is less than a threshold. In particular, the controller may determine whether one or more impedances remain within a steady state over a period Δt. When the change in impedance Δt is below the threshold εi, the controller may, based on the change in impedance, update Imp. Baselinemay be defined. In one aspect, in response to determining that the change is less than a threshold, the controller may use one or more impedances to determine Imp Baseline For example, the controller may define Imp Baseline as the average impedance over one or more impedances, in which case |Imp(t)-Imp(t + Δt)| < ∈ Next, Imp Baseline = average(Imp(t), Imp(t + 1),..., Imp(t + Δt))

[0096] In some aspects, the controller may update the baseline impedance when the ultrasonic device switches from a heating cycle to a cooling cycle. In particular, the controller may determine that the ultrasonic device is in a heating cycle (e.g., the end effector is in a closed position), and in response to determining that the ultrasonic device has returned to a cooling cycle (e.g., the end effector is currently in an open position and / or in air), the controller may monitor (e.g., start) the impedance of the end effector over a period of time to determine a new baseline impedance. In some aspects, the new baseline impedance may be different from the previously determined baseline impedance. This may be due to differences in the monitored impedance, which may be caused by various factors (e.g., the length of time the end effector was in the heating cycle before returning to the cooling cycle, etc.).

[0097] As described above, one aspect of the present disclosure may be a non-transitory machine-readable medium (such as a microelectronic memory) having stored thereon instructions for programming one or more data processing components (herein generally referred to as "processors") to perform (automatically) ultrasonic instrument operations, temperature estimation operations, and / or immersion and / or object contact detection operations as described herein. In other aspects, some of these operations may be performed by specific hardware components including hardwired logic. These operations may alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[0098] Although specific aspects have been described and shown in the accompanying drawings, such aspects are merely illustrative of the broad disclosure and do not limit the broad disclosure, and various other modifications may be contemplated by those skilled in the art, so it should be understood that the present disclosure is not limited to the specific structures and arrangements shown and described. Accordingly, this description should be regarded as illustrative rather than limiting.

[0099] In some aspects, the present disclosure may include, for example, language such as "at least one of [element A] and [element B]". This language may refer to one or more of the elements. For example, "at least one of A and B" may refer to "A", "B", or "A and B". Specifically, "at least one of A and B" may refer to "at least one of A and at least one of B", or "at least one of either A or B". In some aspects, the present disclosure may include, for example, language such as "[element A], [element B], and / or [element C]". This language may refer to any one of the elements or any combination thereof. For example, "A, B, and / or C" may refer to "A", "B", "C", "A and B", "A and C", "B and C", or "A, B, and C".

[0100] 〔Embodiment〕 (1) A method performed by a surgical system, the method comprising: determining one or more characteristics of an end effector of an ultrasonic instrument; based on the one or more determined characteristics, determining that the end effector is at least partially immersed in a liquid; and in response, displaying a notification on a display of the surgical system indicating that the end effector is at least partially immersed in the liquid. (2) The one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed in a liquid includes determining that the impedance exceeds an impedance threshold, the method according to Embodiment 1. (3) The one or more characteristics include the resonant frequency of the end effector, and determining that the end effector is at least partially immersed in a liquid further includes determining that the resonant frequency is less than a resonant frequency threshold, the method according to Embodiment 2. (4) Further including determining the type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, and the notification indicates the type of the liquid, the method according to Embodiment 1. (5) The one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed in a liquid includes determining that the impedance exceeds a first threshold, and the method further includes determining that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold, the method according to Embodiment 1.

[0101] (6) The notification indicates that the end effector is in contact with an object while immersed in a liquid, the method according to Embodiment 5. (7) While the end effector is in air, determining the temperature of the end effector; displaying the temperature on the display; and in response to determining that the end effector is at least partially immersed in a liquid, replacing the temperature with an estimated temperature of the liquid, the method according to Embodiment 1. (8) A surgical system, an ultrasonic instrument having an end effector; a display; a processor; A memory having instructions that, when executed by the processor, cause the surgical system to determine one or more characteristics of the end effector of the ultrasonic instrument, determine, based on the one or more determined characteristics, that the end effector is at least partially immersed in a liquid, and in response, cause a notification indicating that the end effector is at least partially immersed in the liquid to be displayed on the display. A surgical system comprising a memory. (9) The one or more characteristics include the impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed include instructions for determining that the impedance exceeds an impedance threshold. The surgical system according to embodiment 8. (10) The one or more characteristics include the resonant frequency of the end effector, and the instructions for determining that the end effector is at least partially immersed further include instructions for determining that the resonant frequency is less than a resonant frequency threshold. The surgical system according to embodiment 9.

[0102] (11) The memory has further instructions for determining the type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, and the notification indicates the type of liquid. The surgical system according to embodiment 8. (12) The one or more characteristics include the impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed include instructions for determining that the impedance exceeds a first threshold. The memory has further instructions for determining that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold. The surgical system according to embodiment 8. (13) The surgical system according to embodiment 12, wherein the notification indicates that the end effector is in contact with an object while being immersed in a liquid. (14) The memory while the end effector is in air, determines the temperature of the end effector, displays the temperature on the display, and in response to determining that the end effector is at least partially immersed in a liquid, has further instructions to replace the temperature with an estimated temperature of the liquid, the surgical system according to embodiment 8. (15) A non - transitory machine - readable medium having instructions that, when executed by a processor, cause a surgical system to cause the surgical system to determine one or more characteristics of an end effector of an ultrasonic instrument, based on the one or more determined characteristics, determine that the end effector is at least partially immersed in a liquid, and in response, cause a notification indicating that the end effector is at least partially immersed in the liquid to be displayed on a display of the surgical system.

[0103] (16) The one or more characteristics include the impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed in a liquid include instructions for determining that the impedance exceeds an impedance threshold, the non - transitory machine - readable medium according to embodiment 15. (17) The one or more characteristics include the resonant frequency of the end effector, and the instructions for determining that the end effector is at least partially immersed in a liquid further include instructions for determining that the resonant frequency is less than a resonant - frequency threshold, the non - transitory machine - readable medium according to embodiment 16. Having further instructions for determining the type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, the notification being the non-transitory machine-readable medium according to embodiment 15 indicating the type of liquid. (19) The one or more characteristics include the impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed include instructions for determining that the impedance exceeds a first threshold, the non-transitory machine-readable medium having further instructions for determining that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold, the non-transitory machine-readable medium according to embodiment 15. (20) The notification is the non-transitory machine-readable medium according to embodiment 19 indicating that the end effector is in contact with an object while immersed in a liquid.

[0104] (21) While the end effector is in air, determine the temperature of the end effector, display the temperature on the display, and having further instructions for replacing the temperature with an estimated temperature of the liquid in response to determining that the end effector is at least partially immersed, the non-transitory machine-readable medium according to embodiment 15.

Claims

1. A method implemented by a surgical system, the method comprising: determining one or more characteristics of an end effector of an ultrasonic instrument; based on the determined one or more characteristics, determining that the end effector is at least partially immersed in a liquid; in response thereto, displaying on a display of the surgical system a notification indicating that the end effector is at least partially immersed in the liquid.

2. The one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed in a liquid includes determining that the impedance exceeds an impedance threshold. The method according to claim 1.

3. The one or more characteristics include the resonant frequency of the end effector, and determining that the end effector is at least partially immersed in a liquid further includes determining that the resonant frequency is less than a resonant frequency threshold. The method according to claim 2.

4. The method further includes determining, based on the one or more characteristics, the type of liquid in which the end effector is at least partially immersed, and the notification indicates the type of liquid. The method according to claim 1.

5. The one or more characteristics include the impedance of the end effector, and determining that the end effector is at least partially immersed in a liquid includes determining that the impedance exceeds a first threshold. The method further includes determining that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold. The method according to claim 1.

6. The notification indicates that the end effector is in contact with an object while immersed in a liquid. The method according to claim 5.

7. while the end effector is in air, determining the temperature of the end effector; displaying the temperature on the display; and in response to determining that the end effector is at least partially immersed in a liquid, replacing the temperature with an estimated temperature of the liquid. The method according to claim 1.

8. A surgical system, an ultrasonic instrument having an end effector; The display and a processor; a memory having instructions that, when executed by the processor, cause the surgical system to: determining one or more characteristics of the end effector of the ultrasonic instrument; determining that the end effector is at least partially immersed in a liquid based on the determined one or more characteristics; and in response, causing a notification to be displayed on the display indicating that the end effector is at least partially immersed in the liquid.

9. 9. The surgical system of claim 8, wherein the one or more characteristics include an impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed in liquid include instructions for determining that the impedance is above an impedance threshold.

10. 10. The surgical system of claim 9, wherein the one or more characteristics include a resonant frequency of the end effector, and wherein the instructions for determining that the end effector is at least partially immersed in liquid further include instructions for determining that the resonant frequency is below a resonant frequency threshold.

11. 9. The surgical system of claim 8, wherein the memory further comprises instructions for determining a type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, and wherein the notification indicates the type of liquid.

12. 9. The surgical system of claim 8, wherein the one or more characteristics include an impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed in liquid include instructions for determining that the impedance is above a first threshold, and the memory further has instructions for determining that the end effector is in contact with an object while at least partially immersed in liquid in response to the impedance being above a second threshold that is greater than the first threshold.

13. The surgical system of claim 12 , wherein the notification indicates that the end effector is in contact with an object while immersed in a liquid.

14. The memory includes: While the end effector is in air, determining a temperature of the end effector; display the temperature on the display, The surgical system according to claim 8, further comprising instructions for replacing the temperature with an estimated temperature of the liquid in response to determining that the end effector is at least partially immersed in the liquid.

15. A non-transitory machine-readable medium having instructions that, when executed by a processor, cause a surgical system to cause the surgical system to determine one or more characteristics of an end effector of an ultrasonic instrument, determine, based on the one or more determined characteristics, that the end effector is at least partially immersed in a liquid, and in response, display a notification indicating that the end effector is at least partially immersed in the liquid on a display of the surgical system.

16. The one or more characteristics include an impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed in the liquid include instructions for determining that the impedance exceeds an impedance threshold. The non-transitory machine-readable medium according to claim 15.

17. The one or more characteristics include a resonance frequency of the end effector, and the instructions for determining that the end effector is at least partially immersed in the liquid further include instructions for determining that the resonance frequency is less than a resonance frequency threshold. The non-transitory machine-readable medium according to claim 16.

18. The non-transitory machine-readable medium according to claim 15, further comprising instructions for determining a type of liquid in which the end effector is at least partially immersed based on the one or more characteristics, wherein the notification indicates the type of liquid.

19. The one or more characteristics include an impedance of the end effector, and the instructions for determining that the end effector is at least partially immersed in the liquid include instructions for determining that the impedance exceeds a first threshold. The non-transitory machine-readable medium further includes instructions for determining that the end effector is in contact with an object while at least partially immersed in the liquid in response to the impedance exceeding a second threshold greater than the first threshold. The non-transitory machine-readable medium according to claim 15.

20. The non-transitory machine-readable medium according to claim 19, wherein the notification indicates that the end effector is in contact with an object while being immersed in a liquid. **Claim 21** While the end effector is in air, determine the temperature of the end effector, display the temperature on the display, and having further instructions to replace the temperature with an estimated temperature of the liquid in response to determining that the end effector is at least partially immersed, the non-transitory machine-readable medium according to claim 15.

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