DE60333225D1 - Tragbare vorrichtung für die bioelektrische interaktion mit bewegungsartefakt-korrekturmitteln - Google Patents

Tragbare vorrichtung für die bioelektrische interaktion mit bewegungsartefakt-korrekturmitteln

Info

Publication number
DE60333225D1
DE60333225D1 DE60333225T DE60333225T DE60333225D1 DE 60333225 D1 DE60333225 D1 DE 60333225D1 DE 60333225 T DE60333225 T DE 60333225T DE 60333225 T DE60333225 T DE 60333225T DE 60333225 D1 DE60333225 D1 DE 60333225D1
Authority
DE
Germany
Prior art keywords
individual
interaction
pressure sensor
electrode
signal
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.)
Expired - Lifetime
Application number
DE60333225T
Other languages
English (en)
Inventor
Ralf Schmidt
Olaf Such
Christian Reichinger
Michael Perkuhn
Harald Reiter
Andras Montvay
Josef Lauter
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.)
Philips Intellectual Property and Standards GmbH
Original Assignee
Philips Intellectual Property and Standards GmbH
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
Application filed by Philips Intellectual Property and Standards GmbH filed Critical Philips Intellectual Property and Standards GmbH
Application granted granted Critical
Publication of DE60333225D1 publication Critical patent/DE60333225D1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/02Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/0002Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
    • A61B5/0004Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network characterised by the type of physiological signal transmitted
    • A61B5/0006ECG or EEG signals
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/02Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02438Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/02Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02444Details of sensor
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/24Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25Bioelectric electrodes therefor
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/24Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25Bioelectric electrodes therefor
    • A61B5/251Means for maintaining electrode contact with the body
    • A61B5/256Wearable electrodes, e.g. having straps or bands
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/24Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316Modalities, i.e. specific diagnostic methods
    • A61B5/318Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A61B5/332Portable devices specially adapted therefor
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/68Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6843Monitoring or controlling sensor contact pressure
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02Details of sensors specially adapted for in-vivo measurements
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0247Pressure sensors
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/04Arrangements of multiple sensors of the same type
    • A61B2562/046Arrangements of multiple sensors of the same type in a matrix array

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Medical Informatics (AREA)
  • Surgery (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Veterinary Medicine (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Public Health (AREA)
  • Molecular Biology (AREA)
  • Physics & Mathematics (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Cardiology (AREA)
  • Physiology (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
  • Electrotherapy Devices (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
DE60333225T 2002-12-10 2003-12-08 Tragbare vorrichtung für die bioelektrische interaktion mit bewegungsartefakt-korrekturmitteln Expired - Lifetime DE60333225D1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP02080213 2002-12-10
PCT/IB2003/005805 WO2004052190A1 (en) 2002-12-10 2003-12-08 A wearable device for bioelectrical interaction with motion artifact correction means

Publications (1)

Publication Number Publication Date
DE60333225D1 true DE60333225D1 (de) 2010-08-12

Family

ID=32479766

Family Applications (1)

Application Number Title Priority Date Filing Date
DE60333225T Expired - Lifetime DE60333225D1 (de) 2002-12-10 2003-12-08 Tragbare vorrichtung für die bioelektrische interaktion mit bewegungsartefakt-korrekturmitteln

Country Status (8)

Country Link
US (1) US7395105B2 (de)
EP (1) EP1575424B1 (de)
JP (1) JP2006508752A (de)
CN (1) CN100548208C (de)
AT (1) ATE472292T1 (de)
AU (1) AU2003302879A1 (de)
DE (1) DE60333225D1 (de)
WO (1) WO2004052190A1 (de)

Families Citing this family (78)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9247901B2 (en) 2003-08-22 2016-02-02 Dexcom, Inc. Systems and methods for replacing signal artifacts in a glucose sensor data stream
US7497827B2 (en) 2004-07-13 2009-03-03 Dexcom, Inc. Transcutaneous analyte sensor
US8260393B2 (en) 2003-07-25 2012-09-04 Dexcom, Inc. Systems and methods for replacing signal data artifacts in a glucose sensor data stream
US8010174B2 (en) 2003-08-22 2011-08-30 Dexcom, Inc. Systems and methods for replacing signal artifacts in a glucose sensor data stream
US9282925B2 (en) 2002-02-12 2016-03-15 Dexcom, Inc. Systems and methods for replacing signal artifacts in a glucose sensor data stream
US8275437B2 (en) 2003-08-01 2012-09-25 Dexcom, Inc. Transcutaneous analyte sensor
US8845536B2 (en) 2003-08-01 2014-09-30 Dexcom, Inc. Transcutaneous analyte sensor
US20190357827A1 (en) 2003-08-01 2019-11-28 Dexcom, Inc. Analyte sensor
US7774145B2 (en) 2003-08-01 2010-08-10 Dexcom, Inc. Transcutaneous analyte sensor
US20140121989A1 (en) 2003-08-22 2014-05-01 Dexcom, Inc. Systems and methods for processing analyte sensor data
US7920906B2 (en) 2005-03-10 2011-04-05 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
FI118753B (fi) * 2003-10-03 2008-03-14 Suunto Oy Menetelmä sydämen lyöntien tunnistamiseksi ja siitä saatavien suureiden laskemiseksi
US8615282B2 (en) 2004-07-13 2013-12-24 Dexcom, Inc. Analyte sensor
US9247900B2 (en) 2004-07-13 2016-02-02 Dexcom, Inc. Analyte sensor
US8364231B2 (en) 2006-10-04 2013-01-29 Dexcom, Inc. Analyte sensor
US8774886B2 (en) 2006-10-04 2014-07-08 Dexcom, Inc. Analyte sensor
EP1711791B1 (de) 2003-12-09 2014-10-15 DexCom, Inc. Signalverarbeitung für kontinuierlich arbeitenden analytsensor
US8792955B2 (en) 2004-05-03 2014-07-29 Dexcom, Inc. Transcutaneous analyte sensor
US20070045902A1 (en) 2004-07-13 2007-03-01 Brauker James H Analyte sensor
EP3666187B1 (de) * 2004-07-13 2021-05-26 DexCom, Inc. Transkutaner analytsensor
DE102004063249A1 (de) * 2004-12-23 2006-07-13 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Sensorsystem und Verfahren zur kapazitiven Messung elektromagnetischer Signale biologischen Ursprungs
JP5356805B2 (ja) * 2005-04-19 2013-12-04 コーニンクレッカ フィリップス エヌ ヴェ ユーザの生体電気信号を測定するためのシステム及び方法
US8730031B2 (en) 2005-04-28 2014-05-20 Proteus Digital Health, Inc. Communication system using an implantable device
DE102005022005B4 (de) * 2005-05-09 2014-10-30 Anna Gutmann Verfahren und Gerät zur Erleichterung der Bewegungskontrolle von Körperteilen
WO2007025382A1 (en) * 2005-09-01 2007-03-08 Les Systèmes Nuax Computer mouse pressure acquisition module
CA2649250A1 (en) 2006-04-11 2007-10-25 Eisai R & D Management Co., Ltd. Dopaminergic neuron progenitor cell marker 187a5
US7708028B2 (en) 2006-12-08 2010-05-04 Praxair Technology, Inc. Fail-safe vacuum actuated valve for high pressure delivery systems
US20110105874A1 (en) * 2007-08-20 2011-05-05 Koninklijke Philips Electronics N.V. Method for measuring body parameters
US7905247B2 (en) 2008-06-20 2011-03-15 Praxair Technology, Inc. Vacuum actuated valve for high capacity storage and delivery systems
MX2011000090A (es) 2008-06-23 2011-03-02 Janssen Pharmaceutica Nv Forma cristalina de (2s)-(-)-n-(6-cloro-2,3-dihidro-benzo[1,4]diox in-2-ilmetil)sulfamida.
US9737225B2 (en) 2008-06-24 2017-08-22 Biosense Webster, Inc. Patch and sensor assembly for use in medical device localization and mapping systems
US9014778B2 (en) * 2008-06-24 2015-04-21 Biosense Webster, Inc. Disposable patch and reusable sensor assembly for use in medical device localization and mapping systems
GB0814533D0 (en) * 2008-08-08 2008-09-17 Ntnu Technology Transfer As Measurement of bio-signals
US8082025B2 (en) * 2008-08-14 2011-12-20 David Amitai ECG data acquisition device
US11375938B2 (en) 2008-08-14 2022-07-05 Ticker Medical Ltd Miniature ECG data acquisition device
US9659423B2 (en) 2008-12-15 2017-05-23 Proteus Digital Health, Inc. Personal authentication apparatus system and method
US9439566B2 (en) 2008-12-15 2016-09-13 Proteus Digital Health, Inc. Re-wearable wireless device
WO2011007292A1 (en) * 2009-07-13 2011-01-20 Koninklijke Philips Electronics N.V. Electro-physiological measurement with reduced motion artifacts
CN102469957B (zh) * 2009-07-20 2015-09-30 皇家飞利浦电子股份有限公司 用于操作监测***的方法
JP5368904B2 (ja) * 2009-07-28 2013-12-18 トヨタ自動車株式会社 車両用心電計測装置
US20110092780A1 (en) * 2009-10-16 2011-04-21 Tao Zhang Biosensor module with automatic power on capability
US8311605B2 (en) * 2009-10-16 2012-11-13 Affectiva, Inc. Biosensor with pressure compensation
US8774893B2 (en) 2009-10-16 2014-07-08 Affectiva, Inc. Biosensor module with leadless contacts
US8380295B2 (en) * 2009-10-30 2013-02-19 Medtronic, Inc. Detection of waveform artifact
WO2011094606A2 (en) * 2010-02-01 2011-08-04 Proteus Biomedical, Inc. Data gathering system
US8229537B2 (en) * 2010-03-17 2012-07-24 General Electric Company Motion artifact rejection microelectrode
US9375179B2 (en) 2010-12-23 2016-06-28 Biosense Webster, Inc. Single radio-transparent connector for multi-functional reference patch
EP2683291B1 (de) 2011-03-11 2019-07-31 Proteus Digital Health, Inc. Am körper tragbare persönliche vorrichtung mit verschiedenen physikalischen konfigurationen
JP6141827B2 (ja) 2011-04-15 2017-06-07 デックスコム・インコーポレーテッド 検体を測定するシステムの作動方法及び該方法を実施するべく構成されたセンサシステム
WO2015112603A1 (en) 2014-01-21 2015-07-30 Proteus Digital Health, Inc. Masticable ingestible product and communication system therefor
US9756874B2 (en) 2011-07-11 2017-09-12 Proteus Digital Health, Inc. Masticable ingestible product and communication system therefor
KR101832264B1 (ko) * 2011-08-25 2018-04-13 삼성전자주식회사 생체 신호를 측정하는 장치 및 방법
EP2750761B1 (de) 2011-09-01 2022-07-13 Zoll Medical Corporation Tragbare überwachungs- und behandlungsvorrichtung
KR102026740B1 (ko) 2012-02-07 2019-09-30 삼성전자주식회사 생체신호 측정용 전극 및 그 제조방법과, 생체신호 측정 시스템
DE102012014219A1 (de) 2012-02-15 2013-08-22 Alexander von Lühmann Kapazitives Sensorsystem zur Messung von Biopotenzialen mit Anordnung zur Erkennung von Bewegungsartefakten
KR101367596B1 (ko) * 2012-05-15 2014-02-26 주식회사 씨유메디칼시스템 동잡음 측정 및 제거 기능을 포함하는 심장 제세동기
KR101947676B1 (ko) 2012-10-29 2019-02-13 삼성전자주식회사 생체 신호를 측정하는 장치 및 방법
JP6498177B2 (ja) 2013-03-15 2019-04-10 プロテウス デジタル ヘルス, インコーポレイテッド 本人認証装置システムおよび方法
KR102165060B1 (ko) 2013-08-20 2020-10-13 삼성전자주식회사 착용형 생체신호 인터페이스 및 착용형 생체신호 인터페이스의 동작 방법
CN105556912B (zh) 2013-09-20 2019-05-31 普罗秋斯数字健康公司 使用切片和扭曲在存在噪声的情况下接收和解码信号的方法、器件和***
WO2015044722A1 (en) 2013-09-24 2015-04-02 Proteus Digital Health, Inc. Method and apparatus for use with received electromagnetic signal at a frequency not known exactly in advance
US10084880B2 (en) 2013-11-04 2018-09-25 Proteus Digital Health, Inc. Social media networking based on physiologic information
GB2522195A (en) * 2014-01-15 2015-07-22 Imp Innovations Ltd Biosensing electrodes
WO2016065476A1 (en) * 2014-10-30 2016-05-06 2352409 Ontario Inc. A wearable device and method for non-invasive monitoring continuous blood pressure and other physiological parameters with reduced movement artifacts
CN109394185B (zh) * 2014-11-11 2021-04-27 原相科技股份有限公司 具有校正功能的血管感测装置
EP3025644A1 (de) * 2014-11-27 2016-06-01 BIOTRONIK SE & Co. KG Sensoranordnung zur ableitung elektrischer signale
WO2016118974A2 (en) * 2015-01-25 2016-07-28 Aliphcom Physiological characteristics determinator
RU2593797C1 (ru) * 2015-05-06 2016-08-10 Общество С Ограниченной Ответственностью "Хилби" Блок датчиков
JP7251763B2 (ja) * 2016-03-29 2023-04-04 ザ ボード オブ トラスティーズ オブ ザ レランド スタンフォード ジュニア ユニバーシティー ウェアラブル装置、ウェアラブル機器の一部に用いる装置及び血流力学的モニタリング方法
US10722125B2 (en) 2016-10-31 2020-07-28 Livemetric (Medical) S.A. Blood pressure signal acquisition using a pressure sensor array
US11000193B2 (en) 2017-01-04 2021-05-11 Livemetric (Medical) S.A. Blood pressure measurement system using force resistive sensor array
CN106539578A (zh) * 2017-01-09 2017-03-29 广东小天才科技有限公司 一种生理参数检测方法及装置
KR102013495B1 (ko) * 2017-10-25 2019-08-22 울산대학교 산학협력단 생체 정보 측정 센서 및 그 동작 방법
CN110151150B (zh) * 2018-02-12 2022-03-29 财团法人工业技术研究院 生理传感器装置及***、校正方法及穿戴式装置
DE112019001676T5 (de) * 2018-03-29 2020-12-10 Sony Corporation Informationsverarbeitungssystem, informationsverarbeitungsvorrichtung und informationsverarbeitungsverfahren
EP3620109A1 (de) * 2018-09-04 2020-03-11 Koninklijke Philips N.V. Vorrichtung und verfahren zur induktiven messung
MX2021008047A (es) * 2019-01-16 2021-08-05 Medibeacon Inc Montaje de sensor de dos piezas y metodo de uso.
CN110772247A (zh) * 2019-09-19 2020-02-11 北京航空航天大学 一种用于同步同位检测生物电信号与压力信号的传感器件

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2743462B2 (ja) * 1989-05-08 1998-04-22 株式会社デンソー 皮膚電位検出装置
DE69125288T2 (de) 1991-12-27 1997-06-26 Gilles Ascher Elektrodenverbinder, besonders für Elektrokardiogrammelektrode, und zugleich Elektrode mit solch einem Verbinder
US5494043A (en) 1993-05-04 1996-02-27 Vital Insite, Inc. Arterial sensor
US5978693A (en) 1998-02-02 1999-11-02 E.P. Limited Apparatus and method for reduction of motion artifact
US6912414B2 (en) * 2002-01-29 2005-06-28 Southwest Research Institute Electrode systems and methods for reducing motion artifact

Also Published As

Publication number Publication date
ATE472292T1 (de) 2010-07-15
AU2003302879A1 (en) 2004-06-30
JP2006508752A (ja) 2006-03-16
EP1575424A1 (de) 2005-09-21
CN1722976A (zh) 2006-01-18
WO2004052190A1 (en) 2004-06-24
US7395105B2 (en) 2008-07-01
CN100548208C (zh) 2009-10-14
EP1575424B1 (de) 2010-06-30
US20060149146A1 (en) 2006-07-06

Similar Documents

Publication Publication Date Title
DE60333225D1 (de) Tragbare vorrichtung für die bioelektrische interaktion mit bewegungsartefakt-korrekturmitteln
CY1108956T1 (el) Χαρακτηρισμος ανθρωπινου δερματος αναφορικα με ογκο δια ηλεκτρικης αγωγιμωτητας
WO2002013690B1 (en) Capacitively coupled electrode system for sensing voltage potentials at the surface of tissue
WO2005036096A3 (en) Measuring vector components of an electric field
AU2003283226A1 (en) Measuring electrode system
SE9901056D0 (sv) Sensor system
JP5612788B1 (ja) 人体部位検知方法とそれに使用する人体部位検知器及び人体部位検知装置
EP1027861A4 (de) Körperfettanzeiger und damit ausgestattete personenwaage
GB2421082A (en) Protective apparel having contactless physiological sensing electrodes
CN101441512B (zh) 基于压阻传感器的指尖力反馈装置
WO2009036770A3 (en) Electrode connection monitoring
CN210990263U (zh) 自供电柔性电极的智能可穿戴组件及智能可穿戴***
Prakash et al. Novel force myography sensor to measure muscle contractions for controlling hand prostheses
KR20200082891A (ko) 센서 패치
US20040015094A1 (en) Measuring device
WO2008083311A3 (en) Pressure-sensitive conductive composite contact sensor and method for contact sensing
CN106377266A (zh) 一种基于眼部识别的疲劳监测装置
JP2008295867A (ja) 生体信号計測装置
JPS6461626A (en) Unit type distribution pressure sensor
CN210199703U (zh) 一种基于超级电容感知原理的柔性触觉手套
WO2002074383A3 (en) Spread spectrum measurement device
CN207168488U (zh) 一种监测***
Fernandes et al. Wearable brain cap with contactless electroencephalogram measurement for brain-computer interface applications
KR20060000701A (ko) 반지형 생체신호 감지센서 및 반지형 생체신호 감지센서가구비된 생체신호 측정장치
WO2004030537A3 (fr) Dispositif et procede de mesure directe de ph et d'etat d'oxydation