A tracker, a surgical navigation system with the tracker, and a method of operating the tracker are described. The tracker comprises a first switch configured to be operated between a first switch configuration and a second switch configuration. The tracker also comprises one or more sources of electromagnetic radiation configured to selectively emit electromagnetic radiation with a first radiation characteristic or a second radiation characteristic. The tracker further comprises electrical circuitry configured to selectively control the one or more sources of electromagnetic radiation to emit electromagnetic radiation having the first radiation characteristic in the first switch configuration and to emit electromagnetic radiation having the second radiation characteristic in the second switch configuration, wherein the second radiation characteristic is different from the first radiation characteristic.

Various embodiments are described herein for a device for using acoustic or mechanical energy to perform an action at a target site of an object. The device comprises a conduit having an aperture disposed at the target site, a displacement signal source for generating a mechanical displacement signal, a coupling assembly having for coupling the displacement signal source to the conduit, a pressure controller coupled to the proximal end of the conduit to vary an amount of pressure in the conduit when obtaining a first entity from or delivering a second entity to the target site, and a control unit for controlling the displacement signal source to generate the mechanical displacement signal based on a desired acoustic or mechanical wave mode.

A method of controlling the temperature of an ultrasonic blade includes applying a power level to an ultrasonic transducer to achieve a desired temperature at an ultrasonic blade coupled to the transducer via an ultrasonic waveguide, inferring a temperature of the blade based on a voltage V.sub.g(t) signal and a current I.sub.g(t) signal applied to the transducer, comparing the inferred temperature of the blade to a predetermined temperature; and adjusting the power level to the transducer based on the comparison. In some aspects, the method includes measuring a phase angle ? between the voltage V.sub.g(t) and the current I.sub.g(t) and inferring the temperature of the blade from the phase angle ?. In some aspects, the method includes measuring an impedance Z.sub.g(t) equal to a ratio of the voltage V.sub.g(t) to the current I.sub.g(t) and inferring the temperature of the blade from the impedance Z.sub.g(t).

An ultrasonic device may include an electromechanical ultrasonic system having a resonant frequency, the system including a transducer coupled to an ultrasonic blade. A method of driving the blade may include determining a tissue type contacting the blade, setting current delivered to the transducer to achieve a desired blade temperature, and setting a desired period during which the desired temperature is applied to the tissue. The tissue type may be determined by measuring an impedance of the transducer, comparing an impedance measurement data point to a reference data point, and classifying the impedance measurement data point based on a result of the comparison. Alternatively, the tissue type may be determined by applying a drive signal to the transducer, sweeping the frequency of the drive signal from below to above a resonance of the ultrasonic system, measuring and recording impedance/admittance variables, and comparing the measured variables to reference variables

Various aspects of a generator, ultrasonic device, and method for estimating and controlling a state of an end effector of an ultrasonic device are disclsoed. The ultrasonic device includes an electromechanical ultrasonic system defined by a predetermined resonant frequency, including an ultrasonic transducer coupled to an ultrasonic blade. A control circuit measures a complex impedance of an ultrasonic transducer, wherein the complex impedance is defined as

[00001]$Z_g?\left(t\right)=\frac{V_g?\left(t\right)}{I_g?\left(t\right)}.$

The control circuit receives a complex impedance measurement data point and compares the complex impedance measurement data point to a data point in a reference complex impedance characteristic pattern. The control circuit then classifies the complex impedance measurement data point based on a result of the comparison analysis and assigns a state or condition of the end effector based on the result of the comparison analysis. The control circuit estimates the state of the end effector of the ultrasonic device and controls the state of the end effector of the ultrasonic device based on the estimated state.

A method of controlling the temperature of an ultrasonic blade between two temperature set points includes applying a first power level to an ultrasonic transducer to set an ultrasonic blade temperature to a first target temperature T1, monitoring a phase angle ? between voltage V.sub.g(t) and current I.sub.g(t) signals applied to the transducer, inferring the temperature of the blade based on the phase angle ?, determining that a transection process is complete, and applying a second power level to the transducer to set the blade temperature to a second target temperature T2. The transducer may be coupled to the blade via an ultrasonic waveguide. The first target temperature may be optimized for vessel sealing and the second target temperature may be optimized for clamp arm pad life. The control circuit may determine that transection is complete by determining that the ultrasonic blade contacts the clamp arm pad.

An ultrasonic device may include an electromechanical ultrasonic system defined by a predetermined resonant frequency, the electromechanical ultrasonic system further including an ultrasonic transducer coupled to an ultrasonic blade. A method of delivering energy to the ultrasonic device may include measuring a complex impedance of the ultrasonic blade coupled to the ultrasonic transducer, comparing the measured complex impedance to stored values of complex impedance patterns associated with ultrasonic blade functions, and applying, an algorithm to control a power output to the ultrasonic transducer based on the comparison. The method may further include delivering energy to the ultrasonic device based on a state or condition of an end effector, in which the state or condition of the end effector corresponds to a state of only sealing a tissue or of spot coagulating the tissue.

An ultrasonic device may include an electromechanical ultrasonic system that includes an ultrasonic transducer coupled to an ultrasonic blade. A method of delivering energy to the ultrasonic device may include sensing a vessel type in contact with the blade, determining that the vessel type is either a vein or an artery, and delivering power to the transducer based on the vessel type. Power may be applied to the transducer at a power level P that differs from a nominal power level Pn for a period T that differs from a nominal period Tn based on the vessel. The power level P may be lower than Pn for a period T that is longer than Tn when the vessel is a vein. Alternatively, the power level P my be greater than Pn for a period T that is shorter than Tn when the vessel is an artery.

A method of determining instability of an ultrasonic blade includes monitoring a phase angle ? between voltage Vg(t) and current Ig(t) signals applied to an ultrasonic transducer, coupled to an ultrasonic blade via an ultrasonic waveguide, inferring the blade temperature based on the phase angle ?, comparing the inferred temperature to an ultrasonic blade instability trigger point threshold, and adjusting a power level applied to the ultrasonic transducer to modulate the temperature of the blade. The method may also include determining a frequency/temperature relationship of an ultrasonic blade that exhibits a displacement or modal instability and compensating for a thermal induced instability of the ultrasonic blade. The method may be implemented in an ultrasonic surgical instrument or by a control circuit in a power generator for the ultrasonic surgical instrument.

An ultrasonic device may include an ultrasonic system including a transducer coupled to an ultrasonic blade, A method of delivering energy to the device may include sensing a vessel contacting the blade, identifying that the vessel is calcified, and generating a warning. In some aspects, the method further includes disabling one or more activation functions of the blade. In another aspect, the method further includes generating a message to apply compression to the vessel for a predetermined period, disabling activation functions of the blade during compression, and enabling activation functions after the expiration of the compression period. In yet another aspect, the method includes applying a compressive clamp force to the calcified vessel by driving a clamp arm toward the blade, disabling activation functions of the blade during compression, and enabling the activation functions after adjusting the compressive force. An ultrasonic surgical instrument may effect the method.