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


Oslo Bioimpedance GroupPhD-students: Christian Tronstad, Bernt Norbotten, Per Høyum, Azar Jabbari,Fred Johan Pettersen, Gorm Krogh Johnsen & Håvard Kalvøy

Professor Sverre Grimnes


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


• 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


Cut down or percutaneous(with ultrasound – Per Kristian Hol)


Collecting tissue data


Classification – arteries and veinsone outlier removed


Classification – muscle and fat


Classification – subdermis and fat


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.


Invasive 2D imaging?

• Data available only fewweeks ago

• No classification yet• Simple plot of phase

angle at 100 kHz


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Unpublished results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


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


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


During physical excercise


During sleep

Currently high focus on time series parameterization


www.fys.uio.no/elg/bioimpwww.fys.uio.no/elg/bioimp

Ørjan G. Martinsen - SINTEF...Oslo Bioimpedance Group - 1 Bioimpedance based sensors Ørjan G....

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