GB2317566A - Electrosurgery apparatus waveform generator - Google Patents

Electrosurgery apparatus waveform generator Download PDF

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Publication number
GB2317566A
GB2317566A GB9718316A GB9718316A GB2317566A GB 2317566 A GB2317566 A GB 2317566A GB 9718316 A GB9718316 A GB 9718316A GB 9718316 A GB9718316 A GB 9718316A GB 2317566 A GB2317566 A GB 2317566A
Authority
GB
United Kingdom
Prior art keywords
connected
transformer
primary winding
sine wave
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9718316A
Other versions
GB2317566B (en
GB9718316D0 (en
Inventor
Stewart James John Hay
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Smiths Group PLC
Original Assignee
Smiths Group PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GBGB9620127.2A priority Critical patent/GB9620127D0/en
Application filed by Smiths Group PLC filed Critical Smiths Group PLC
Priority to GB9718316A priority patent/GB2317566B/en
Publication of GB9718316D0 publication Critical patent/GB9718316D0/en
Publication of GB2317566A publication Critical patent/GB2317566A/en
Application granted granted Critical
Publication of GB2317566B publication Critical patent/GB2317566B/en
Anticipated expiration legal-status Critical
Application status is Expired - Fee Related legal-status Critical

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/1206Generators therefor
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00636Sensing and controlling the application of energy
    • A61B2018/0066Sensing and controlling the application of energy without feedback, i.e. open loop control

Abstract

Waveform generator 2 supplies a 350 kHz square wave or sine wave output from a transformer 11 to an active hand-held electrosurgical electrode 5. Primary winding 15 of transformer 11 is connected to MOSFET switches 17,18 driven by a gate logic circuit 20, and to a modulating transistor 28 driven by the output of a sine wave generator 30 which includes a resonant LC circuit and transformer 32. The transistor 28 is connected to a 100 volt DC source 26 and provides full wave rectified sine wave voltage to transformer 11 when a sinusoidal output is required. When a square wave output is required, the transistor 28 is shunted by a manual switch 29 so that DC voltage is supplied to the centre tap 25 of primary winding 15.

Description

ELECTROSURGERY APPARATUS This invention relates to electrosurgery apparatus and to waveform generators for such apparatus.

Electrosurgery, or diathermy, employs high frequency electrical currents to produce cutting, coagulation, or a combination of both cutting and coagulation of patient tissue. The effect produced depends largely on the nature of the pulses applied to the electrosurgery electrode. Where the apparatus must be capable of producing both a square wave and a sine wave output, this is achieved by two separate circuits and by connecting the electrode to the desired circuit. This is a disadvantage because it increases the cost, complexity, size and weight of the apparatus.

It is an object of the present invention to provide improved electrosurgery apparatus.

According to one aspect of the present invention there is provided electrosurgery apparatus including an output transformer having a primary winding and a secondary winding, the apparatus including first and second switch means connected between ground and respective opposite ends of the primary winding, means for alternately gating the first and second switch means so that one switch is closed while the other switch is open, and a drive circuit connected to a centre tap of the primary winding, the drive circuit being selectable to supply either a steady voltage to the centre tap when a square wave output is desired across the secondary winding or an alternating sine wave when a sine wave output is desired across the secondary winding The first and second switch means may include a MOSFET transistor. The drive circuit preferably includes a dc voltage source connected to the centre tap via modulating means, the apparatus including a sine wave generator connected with the modulating means.

The sine wave generator may be driven by the gating means. The sine wave generator preferably includes a second transformer having a primary winding connected with a capacitance to provide a resonant LC circuit. Opposite ends of the primary winding of the second transformer are preferably connected to ground via respective capacitors, a centre tap of the primary winding being connected to ground via a third switch means, the third switch means being controlled by an output from the gating means. Opposite ends of a secondary winding of the second transformer are preferably connected to ground via respective unidirectional current devices, a centre tap of the secondary winding being connected to provide the drive for the modulating means.

Electrosurgery apparatus according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a circuit diagram of the apparatus; and Figure 2 shows waveforms at different locations in the apparatus.

With reference first to Figure 1, the apparatus is indicated generally by the numeral 1 and includes a waveform generator 2. The apparatus 1 also includes various other conventional features, such as for power control, safety and monitoring, which are not shown because they are not relevant for an understanding of the present invention. The apparatus 1 has output terminals 3 and 4 connected respectively to an active hand-held electrode 5 and a large-area plate, return electrode 6.

The two electrodes 5 and 6 are connected to opposite ends of a secondary winding 10 of an output transformer 11, via respective capacitors 12 and 13. The transformer 11 has a primary winding 15 with opposite ends connected to a ground rail 16 via respective MOSFET transistor switches 17 and 18, the drains of the transistors being connected to the winding.

The waveform generator 2 includes a gate logic circuit 20 connected to the gates of the transistors 17 and 18. The logic circuit 20 produces two identical square-wave outputs of the kind shown in Figures 2B and 2C, the two outputs being 1800 out of phase with each other so that one output is high while the other is low. The high period of each pulse is slightly longer than the low period so that there is a short dead time between the high periods of the two sets of pulses. The logic circuit 20 switches the transistors 17 and 18 on and off altemately, with one transistor being non-conductive while the other is conductive.

The waveform generator 2 also includes a drive circuit 24 connected to the centre tap 25 of the primary winding 15. The drive circuit 24 includes a dc voltage supply 26 producing a dc voltage of about 100 volts on a supply line 27 connected to the centre tap 25. The supply line 27 has a bipolar modulating transistor 28 connected with its collector and emitter in series in the supply line, and a manually-operated switch 29 connected in parallel across the transistor. The base of the transistor 28 is connected to a sine wave generator 30 producing a full-wave rectified sine wave voltage. The generator 30 has a resonant LC circuit where the inductance is provided by the primary winding 31 of a transformer 32 constructed to store an appreciable amount of energy. The centre tap of the primary winding 31 is connected to both the dc voltage supply 26 and to the ground rail 16, via a series connection of a diode 33 and a MOSFET transistor 34. The gate of the transistor 34 is connected to an output of the logic circuit 20, which produces square wave pulses at the desired operating frequency of the waveform generator, typically about 350 kHz. The two opposite ends of the primary winding 31 are connected to the ground rail via respective capacitors 36 and 37 providing the capacitive element ofthe resonant LC circuit. The secondary winding 38 ofthe transformer 32 has its centre tapping connected to the base of the modulating transistor 28. Opposite ends of the secondary winding 38 are connected to the ground rail 16 via respective diodes 39 and 40.

The operation of the apparatus will now be described also with reference to Figure 2.

The pulse input from the logic circuit 20 switches the transistor 34 on and off at the resonant frequency of the LC circuit formed by the primary winding 31 of the transformer 30 and the two capacitors 36 and 37. This produces an alternating sine wave across the primary winding 31. The output at the centre tap of the secondary winding 38 is, therefore, a sine signal full-wave rectified by the diodes 39 and 40. This signal is supplied to the base of the bipolar transistor 28 so that the voltage on the supply rail 27 is modulated accordingly and a full-wave, rectified voltage, of the kind shown in Figure 2A, is supplied to the centre tap 25 of the primary winding 15 of the output transformer 11. The transistors 17 and 18 connected to opposite ends of the primary winding 15 are switched by their inputs shown in Figures 2B and 2C respectively, in synchronism with the alternating signal at the centre tap 25. The signals at the drains of the two transistors 17 and 18 are, therefore, alternating sine wave signals of the kind shown in Figures 2D and 2E respectively. This produces a sine wave output on the secondary winding 10 of the transformer 11 of the kind shown in Figure 2F.

To produce a square wave output instead, the user closes the manual switch 29, so that the transistor 28 is shunted and the centre tap 25 of the primary winding 15 receives a steady dc voltage. The signals at the drains of the two transistors 17 and 18 are then square waves of the kind shown in Figures 2G and 2H respectively. The output on the secondary winding 10 is then an alternating square wave of the kind shown in Figure 21.

The apparatus can, therefore, easily be switched between a sine wave and a square wave output whilst still using the same output transformer.

Claims (9)

1. Electrosurgery apparatus including an output transformer having a primary winding and a secondary winding, wherein the apparatus includes first and second switch means connected between ground and respective opposite ends of the primary winding, means for alternately gating the first and second switch means so that one switch is closed while the other switch is open, and a drive circuit connected to a centre tap of the primary winding, and wherein said drive circuit is selectable to supply either a steady voltage to the centre tap when a square wave output is desired across the secondary winding or an alternating sine wave when a sine wave output is desired across the secondary winding.
2. Electrosurgery apparatus according to Claim l, wherein said first and second switch means include a MOSFET transistor.
3. Electrosurgery apparatus according to Claim 1 or 2, wherein said drive circuit includes a dc voltage source connected to said centre tap via modulating means, and wherein said apparatus includes a sine wave generator connected with the modulating means.
4. Electrosurgery apparatus according to Claim 3, wherein said sine wave generator is driven by said gating means.
5. Electrosurgery apparatus according to Claim 3 or 4, wherein said sine wave generator includes a second transformer having a primary winding connected with a capacitance to provide a resonant LC circuit.
6. Electrosurgery apparatus according to Claim 5, wherein opposite ends of the primary winding of the second transformer are connected to ground via respective capacitors, wherein a centre tap of said primary winding is connected to ground via a third switch means, and wherein said third switch means is controlled by an output from said gating means.
7. Electrosurgery apparatus according to Claim 5 or 6, wherein opposite ends of a secondary winding of the second transformer are connected to ground via respective unidirectional current devices, and wherein a centre tap of said secondary winding is connected to provide the drive for the modulating means.
8 Electrosurgery apparatus substantially as hereinbefore described with reference to the accompanying drawings.
9. Any novel feature or combination of features as hereinbefore described.
GB9718316A 1996-09-27 1997-09-01 Electrosurgery apparatus Expired - Fee Related GB2317566B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GBGB9620127.2A GB9620127D0 (en) 1996-09-27 1996-09-27 Electrosurgery apparatus
GB9718316A GB2317566B (en) 1996-09-27 1997-09-01 Electrosurgery apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9718316A GB2317566B (en) 1996-09-27 1997-09-01 Electrosurgery apparatus

Publications (3)

Publication Number Publication Date
GB9718316D0 GB9718316D0 (en) 1997-11-05
GB2317566A true GB2317566A (en) 1998-04-01
GB2317566B GB2317566B (en) 2000-08-09

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9718316A Expired - Fee Related GB2317566B (en) 1996-09-27 1997-09-01 Electrosurgery apparatus

Country Status (1)

Country Link
GB (1) GB2317566B (en)

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999058070A2 (en) * 1998-05-08 1999-11-18 Novacept A radio-frequency generator for an ablation device
CN101510696B (en) 2009-03-30 2011-04-06 中国科学院等离子体物理研究所 High-power waveform generator
US9339289B2 (en) 2007-11-30 2016-05-17 Ehticon Endo-Surgery, LLC Ultrasonic surgical instrument blades
US9393037B2 (en) 2012-06-29 2016-07-19 Ethicon Endo-Surgery, Llc Surgical instruments with articulating shafts
US9414853B2 (en) 2007-07-27 2016-08-16 Ethicon Endo-Surgery, Llc Ultrasonic end effectors with increased active length
US9504855B2 (en) 2008-08-06 2016-11-29 Ethicon Surgery, LLC Devices and techniques for cutting and coagulating tissue
US9510850B2 (en) 2010-02-11 2016-12-06 Ethicon Endo-Surgery, Llc Ultrasonic surgical instruments
US9623237B2 (en) 2009-10-09 2017-04-18 Ethicon Endo-Surgery, Llc Surgical generator for ultrasonic and electrosurgical devices
US9642644B2 (en) 2007-07-27 2017-05-09 Ethicon Endo-Surgery, Llc Surgical instruments
US9649126B2 (en) 2010-02-11 2017-05-16 Ethicon Endo-Surgery, Llc Seal arrangements for ultrasonically powered surgical instruments
US9700339B2 (en) 2009-05-20 2017-07-11 Ethicon Endo-Surgery, Inc. Coupling arrangements and methods for attaching tools to ultrasonic surgical instruments
US9700343B2 (en) 2012-04-09 2017-07-11 Ethicon Endo-Surgery, Llc Devices and techniques for cutting and coagulating tissue
US9707027B2 (en) 2010-05-21 2017-07-18 Ethicon Endo-Surgery, Llc Medical device
US9713507B2 (en) 2012-06-29 2017-07-25 Ethicon Endo-Surgery, Llc Closed feedback control for electrosurgical device
US9724118B2 (en) 2012-04-09 2017-08-08 Ethicon Endo-Surgery, Llc Techniques for cutting and coagulating tissue for ultrasonic surgical instruments
US9737326B2 (en) 2012-06-29 2017-08-22 Ethicon Endo-Surgery, Llc Haptic feedback devices for surgical robot
US9743947B2 (en) 2013-03-15 2017-08-29 Ethicon Endo-Surgery, Llc End effector with a clamp arm assembly and blade
US9764164B2 (en) 2009-07-15 2017-09-19 Ethicon Llc Ultrasonic surgical instruments
US9795405B2 (en) 2012-10-22 2017-10-24 Ethicon Llc Surgical instrument
US9801648B2 (en) 2007-03-22 2017-10-31 Ethicon Llc Surgical instruments
US9848902B2 (en) 2007-10-05 2017-12-26 Ethicon Llc Ergonomic surgical instruments
US9848901B2 (en) 2010-02-11 2017-12-26 Ethicon Llc Dual purpose surgical instrument for cutting and coagulating tissue
US9883884B2 (en) 2007-03-22 2018-02-06 Ethicon Llc Ultrasonic surgical instruments
US9913656B2 (en) 2007-07-27 2018-03-13 Ethicon Llc Ultrasonic surgical instruments
US9925003B2 (en) 2012-02-10 2018-03-27 Ethicon Endo-Surgery, Llc Robotically controlled surgical instrument
US9962182B2 (en) 2010-02-11 2018-05-08 Ethicon Llc Ultrasonic surgical instruments with moving cutting implement
US10010339B2 (en) 2007-11-30 2018-07-03 Ethicon Llc Ultrasonic surgical blades
US10034684B2 (en) 2015-06-15 2018-07-31 Ethicon Llc Apparatus and method for dissecting and coagulating tissue
US10034704B2 (en) 2015-06-30 2018-07-31 Ethicon Llc Surgical instrument with user adaptable algorithms
US10154852B2 (en) 2015-07-01 2018-12-18 Ethicon Llc Ultrasonic surgical blade with improved cutting and coagulation features
US10179022B2 (en) 2015-12-30 2019-01-15 Ethicon Llc Jaw position impedance limiter for electrosurgical instrument
US10194973B2 (en) 2015-09-30 2019-02-05 Ethicon Llc Generator for digitally generating electrical signal waveforms for electrosurgical and ultrasonic surgical instruments
US10201382B2 (en) 2009-10-09 2019-02-12 Ethicon Llc Surgical generator for ultrasonic and electrosurgical devices
US10226273B2 (en) 2013-03-14 2019-03-12 Ethicon Llc Mechanical fasteners for use with surgical energy devices
US10245065B2 (en) 2018-05-22 2019-04-02 Ethicon Llc Ultrasonic surgical blades

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7604633B2 (en) 1996-04-12 2009-10-20 Cytyc Corporation Moisture transport system for contact electrocoagulation
US8551082B2 (en) 1998-05-08 2013-10-08 Cytyc Surgical Products Radio-frequency generator for powering an ablation device
US8486060B2 (en) 2006-09-18 2013-07-16 Cytyc Corporation Power ramping during RF ablation

Citations (3)

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Publication number Priority date Publication date Assignee Title
US4334539A (en) * 1980-04-28 1982-06-15 Cimarron Instruments, Inc. Electrosurgical generator control apparatus
GB2154881A (en) * 1984-01-25 1985-09-18 Matburn Electrosurgical unit
GB2285750A (en) * 1994-01-19 1995-07-26 Smiths Industries Plc Electrosurgery apparatus

Patent Citations (3)

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US4334539A (en) * 1980-04-28 1982-06-15 Cimarron Instruments, Inc. Electrosurgical generator control apparatus
GB2154881A (en) * 1984-01-25 1985-09-18 Matburn Electrosurgical unit
GB2285750A (en) * 1994-01-19 1995-07-26 Smiths Industries Plc Electrosurgery apparatus

Cited By (49)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999058070A2 (en) * 1998-05-08 1999-11-18 Novacept A radio-frequency generator for an ablation device
WO1999058070A3 (en) * 1998-05-08 2000-02-17 Mark Leo Kane A radio-frequency generator for an ablation device
US6508815B1 (en) 1998-05-08 2003-01-21 Novacept Radio-frequency generator for powering an ablation device
US7074217B2 (en) 1998-05-08 2006-07-11 Cytyc Surgical Products Radio-frequency generator for powering an ablation device
US7407502B2 (en) 1998-05-08 2008-08-05 Cytyc Corporation Radio-frequency generator for powering an ablation device
US7717909B2 (en) 1998-05-08 2010-05-18 Cytyc Surgical Products Radio-frequency generator for powering an ablation device
US9883884B2 (en) 2007-03-22 2018-02-06 Ethicon Llc Ultrasonic surgical instruments
US9801648B2 (en) 2007-03-22 2017-10-31 Ethicon Llc Surgical instruments
US9987033B2 (en) 2007-03-22 2018-06-05 Ethicon Llc Ultrasonic surgical instruments
US9414853B2 (en) 2007-07-27 2016-08-16 Ethicon Endo-Surgery, Llc Ultrasonic end effectors with increased active length
US9642644B2 (en) 2007-07-27 2017-05-09 Ethicon Endo-Surgery, Llc Surgical instruments
US9913656B2 (en) 2007-07-27 2018-03-13 Ethicon Llc Ultrasonic surgical instruments
US9707004B2 (en) 2007-07-27 2017-07-18 Ethicon Llc Surgical instruments
US9848902B2 (en) 2007-10-05 2017-12-26 Ethicon Llc Ergonomic surgical instruments
US10045794B2 (en) 2007-11-30 2018-08-14 Ethicon Llc Ultrasonic surgical blades
US9339289B2 (en) 2007-11-30 2016-05-17 Ehticon Endo-Surgery, LLC Ultrasonic surgical instrument blades
US10010339B2 (en) 2007-11-30 2018-07-03 Ethicon Llc Ultrasonic surgical blades
US10022568B2 (en) 2008-08-06 2018-07-17 Ethicon Llc Devices and techniques for cutting and coagulating tissue
US9795808B2 (en) 2008-08-06 2017-10-24 Ethicon Llc Devices and techniques for cutting and coagulating tissue
US9504855B2 (en) 2008-08-06 2016-11-29 Ethicon Surgery, LLC Devices and techniques for cutting and coagulating tissue
US10022567B2 (en) 2008-08-06 2018-07-17 Ethicon Llc Devices and techniques for cutting and coagulating tissue
CN101510696B (en) 2009-03-30 2011-04-06 中国科学院等离子体物理研究所 High-power waveform generator
US9700339B2 (en) 2009-05-20 2017-07-11 Ethicon Endo-Surgery, Inc. Coupling arrangements and methods for attaching tools to ultrasonic surgical instruments
US9764164B2 (en) 2009-07-15 2017-09-19 Ethicon Llc Ultrasonic surgical instruments
US9623237B2 (en) 2009-10-09 2017-04-18 Ethicon Endo-Surgery, Llc Surgical generator for ultrasonic and electrosurgical devices
US10201382B2 (en) 2009-10-09 2019-02-12 Ethicon Llc Surgical generator for ultrasonic and electrosurgical devices
US10117667B2 (en) 2010-02-11 2018-11-06 Ethicon Llc Control systems for ultrasonically powered surgical instruments
US9649126B2 (en) 2010-02-11 2017-05-16 Ethicon Endo-Surgery, Llc Seal arrangements for ultrasonically powered surgical instruments
US9510850B2 (en) 2010-02-11 2016-12-06 Ethicon Endo-Surgery, Llc Ultrasonic surgical instruments
US9848901B2 (en) 2010-02-11 2017-12-26 Ethicon Llc Dual purpose surgical instrument for cutting and coagulating tissue
US9962182B2 (en) 2010-02-11 2018-05-08 Ethicon Llc Ultrasonic surgical instruments with moving cutting implement
US9707027B2 (en) 2010-05-21 2017-07-18 Ethicon Endo-Surgery, Llc Medical device
US9925003B2 (en) 2012-02-10 2018-03-27 Ethicon Endo-Surgery, Llc Robotically controlled surgical instrument
US9724118B2 (en) 2012-04-09 2017-08-08 Ethicon Endo-Surgery, Llc Techniques for cutting and coagulating tissue for ultrasonic surgical instruments
US9700343B2 (en) 2012-04-09 2017-07-11 Ethicon Endo-Surgery, Llc Devices and techniques for cutting and coagulating tissue
US9393037B2 (en) 2012-06-29 2016-07-19 Ethicon Endo-Surgery, Llc Surgical instruments with articulating shafts
US9737326B2 (en) 2012-06-29 2017-08-22 Ethicon Endo-Surgery, Llc Haptic feedback devices for surgical robot
US9713507B2 (en) 2012-06-29 2017-07-25 Ethicon Endo-Surgery, Llc Closed feedback control for electrosurgical device
US9795405B2 (en) 2012-10-22 2017-10-24 Ethicon Llc Surgical instrument
US10226273B2 (en) 2013-03-14 2019-03-12 Ethicon Llc Mechanical fasteners for use with surgical energy devices
US9743947B2 (en) 2013-03-15 2017-08-29 Ethicon Endo-Surgery, Llc End effector with a clamp arm assembly and blade
US10034684B2 (en) 2015-06-15 2018-07-31 Ethicon Llc Apparatus and method for dissecting and coagulating tissue
US10034704B2 (en) 2015-06-30 2018-07-31 Ethicon Llc Surgical instrument with user adaptable algorithms
US10154852B2 (en) 2015-07-01 2018-12-18 Ethicon Llc Ultrasonic surgical blade with improved cutting and coagulation features
US10194973B2 (en) 2015-09-30 2019-02-05 Ethicon Llc Generator for digitally generating electrical signal waveforms for electrosurgical and ultrasonic surgical instruments
US10179022B2 (en) 2015-12-30 2019-01-15 Ethicon Llc Jaw position impedance limiter for electrosurgical instrument
US10251664B2 (en) 2016-12-16 2019-04-09 Ethicon Llc Modular battery powered handheld surgical instrument with multi-function motor via shifting gear assembly
US10245064B2 (en) 2017-06-19 2019-04-02 Ethicon Llc Ultrasonic surgical instrument with piezoelectric central lumen transducer
US10245065B2 (en) 2018-05-22 2019-04-02 Ethicon Llc Ultrasonic surgical blades

Also Published As

Publication number Publication date
GB2317566B (en) 2000-08-09
GB9718316D0 (en) 1997-11-05

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20020901