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Graphene electrodes for long-term impedance pneumography - a feasibility study

Presentation from EMBEC'17 & NBC'17 conference

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Graphene electrodes for long-term impedance pneumography - a feasibility study

  1. 1. Graphene electrodes for long-term impedance pneumography 
 - a feasibility study Marcel Młyńczak, Marek Żyliński, Daniel Janczak, 
 Małgorzata Jakubowska, Wiktor Niewiadomski and Gerard Cybulski Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering Tampere, June 14, 2017
  2. 2. Introduction Electrodes for bioimpedance measurements 2 Diagnostic electrodes can be devided into: - reusable (silver, tin, gold, sintered Ag/AgCl, platinum or stainless steel); - disposable (Ag/AgCl, delivered with adhesive gel and dry polymer foam). 1. 3.2. 24h Holter measurements Sport 
 medicine Physiological applications
  3. 3. Introduction Problems with disposable Ag/AgCl electrodes 3 Performance changes Impact of sweating Patient discomfort Cables tangling
  4. 4. Introduction How to deal with the problem? 4 Combining the electrodes and integrating them with clothing, which: - protects against detachment, - makes the contact independent of perspiration. Electrodes of this type should be: - durable, - reusable, - resistant to washing.
  5. 5. Introduction Graphene electrodes 5 Graphene-based wearable electrodes, consisting of a thin layer of graphene paste with binding elements seems promising, because: - graphene layers are flexible, not prone to crumbling due to bending, - graphene has low resistance and high tolerance to changes 
 in environmental conditions, - the risk of allergic reaction is lower, as graphene is pure carbon.
  6. 6. Objectives • Preparing the graphene electrodes • Investigating the impedance of the electrode-skin 
 contact of graphene electrodes printed on foil 
 in four different sizes (in circular and square shapes), 
 compared to classical ECG electrodes • Determining the feasibility of using such electrodes 
 for impedance pneumography measurements 6
  7. 7. Graphene electrodes 7 Circle, 14mm Circle, 23mm Circle, 26mm Square, 26mm
  8. 8. Skin-electrode impedance Methodology 8 • Bipolar method • Procedure consisting of 3 frequencies: 100, 200 and 400 Hz • Each electrode tested for 20 minutes • Reference: standard limb clip clamp reusable ECG electrodes
  9. 9. Skin-electrode impedance Results (at 20 minute) 9 Area [cm2] |Z|100Hz [Ω] |Z|200Hz [Ω] |Z|400Hz [Ω] Reference ECG 8.0 11.5 6.2 3.9 Circle, 1.4cm 1.5 209.8 117.3 94.5 Circle, 2.3cm 4.2 42.8 25.3 11.6 Circle, 2.6cm 5.3 61.4 37.0 27.3 Square 6.8 41.1 20.5 13.1
  10. 10. Tidal volume estimation accuracy Methodology 10 IP & ECG electrodes Neutral electrode Pneumonitor 3 Electrode configuration
  11. 11. Tidal volume estimation Methodology 11 • Study participant: generally healthy male, aged 27 • Calibration: 1 minute of free breathing while sitting and standing • Test procedure: regular breathing at two frequencies (10 & 15 BPM), with two depths (shallow and deep), in the same positions • Reference: Flow Measurement System with a Spirometer Unit 
 and a Fleisch-type Heatable Flow Transducer 5530, 
 with a Conical Mouthpiece (Medikro Oy, Finland) • Quantitative assessment: calibration coefficients estimation after signals processing; next comparison of the tidal volumes
  12. 12. Signals acquired in sitting body position 12 Tidal volume estimation
  13. 13. Signals acquired in sitting body position 13 Tidal volume estimation R2 of calibration model: 0.93 Absolute error of TV: 181.3 ml
  14. 14. 14 Signals acquired in standing body position Tidal volume estimation
  15. 15. 15 Signals acquired in standing body position Tidal volume estimation R2 of calibration model: 0.94 Absolute error of TV: 86.5 ml
  16. 16. Discussion Stabilization time Graphene electrodes takes much longer 
 to stabilize than that of silver ones. Size and surface Impact of sweating Compromise between contact impedance and comfort To be evaluated… 16
  17. 17. Summary Presented graphene electrodes are flexible, have flexural strength, and can be prepared with surfaces of any shape. They could be integrated with clothing and probably 
 used in bioimpedance applications, 
 e.g., long-term cardiorespiratory analysis. 17
  18. 18. Tampere, June 14, 2017 Marcel Młyńczak Graphene electrodes for long-term impedance pneumography 
 - a feasibility study