Ørjan G. Martinsen - SINTEF...Oslo Bioimpedance Group - 1 Bioimpedance based sensors Ørjan G....
Transcript of Ørjan G. Martinsen - SINTEF...Oslo Bioimpedance Group - 1 Bioimpedance based sensors Ørjan G....
Oslo Bioimpedance Group - www.fys.uio.no/elg/bioimp 1
Bioimpedance based sensors
Ørjan G. MartinsenProfessor, Dr. Scient.
Department of Physics, University of Oslo, NorwayDept. of Biomed. and Clin. Eng., Rikshospitalet University Hospital, Norway
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Oslo Bioimpedance GroupPhD-students: Christian Tronstad, Bernt Norbotten, Per Høyum, Azar Jabbari,Fred Johan Pettersen, Gorm Krogh Johnsen & Håvard Kalvøy
Professor Sverre Grimnes
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BioimpedanceBasics
• Impedance:• is a measure of the impediment or opposition to the
flow of alternating current• is a complex number. • has an “ohmic” part (free ions) and a capacitive part
(bound ions). • is the inverse of admittance (conductance and
susceptance)
• It:• changes with tissue type, physiology and anatomy• can hence be used as a transducer mechanism for
physiological parameters• can be measured with two, three or four electrodes• can be measured invasively or non-invasively• depends on the measurement frequency
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• Insulated shafts
• Commonly used for EMG• Apply a small electric current between
the needle and a counter-electrode• Measurement sensitivity is ∼ J 2
• With:• Interventional Center, RH• Dept. of Anesthesia, RH• Lærdal Medical• University of Pennsylvania
(Prof. Lance Becker)
Needle positioning
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Cut down or percutaneous(with ultrasound – Per Kristian Hol)
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Collecting tissue data
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Classification – arteries and veinsone outlier removed
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Classification – muscle and fat
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Classification – subdermis and fat
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Needle arrayTo find blood vessels (artery and vein) during Emergency Cardiopulmonary Bypass (ECPB) for hypothermia and controlled reperfusion. The objective is to develop an automatic tool that finds blood vessels and guides the cannulae into the vessels.
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Invasive 2D imaging?
• Data available only fewweeks ago
• No classification yet• Simple plot of phase
angle at 100 kHz
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First invasive impedance tomography image
• No multivariate analysis• No classification
only continuous color• Simple plot of phase
angle at 100 kHz• Looks very promising• Multivariate classification
will greatly increase the image quality
• Step in vs. step out
Unpublished results
Will be added later
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SudoLogger – sweat activity measurementsLow frequency conductance method to focus on the sweat ductsFour skin sites simultaneously, wireless, built-in memory for up to 24 hours, CE-marked
Disorders associated with altered sweating:• Primary hyperhidrosis – palmoplantar, axillary, gustatoric
• Diabetes – secondary hyperhidrose
• Cystic fibrosis – ion concentration
• Ross syndrome – segmental anhidrosis
Other applications:• Electrodermal response (EDR)• Neurology• Stress measurements• Sleep measurements• Biofeedback
With:•Interventional Center, RH•Dept. of Dermatology, RH
With:•Interventional Center, RH•Dept. of Dermatology, RH
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Patient with axillary hyperhidrosis before and after liposuctionDept. of Dermatology (Anne-Lene Krogstad, Per Helsing) Dept. for Plastic Surgery (Khiem Pham)
Acoustic stimulusCognitive stimulusPhysical stimulus
Unpublished results
Will be added later
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During physical excercise
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During sleep
Currently high focus on time series parameterization
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