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High-quality biopotential acquisition without a reference electrode: power-line interference reduction by adaptive impedance balancing in a mixed analog–digital design

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Abstract

Power-line-interference (PLI) is one of the major disturbing factors in almost all ground-free biopotential acquisition applications. The body is a volume conductor and collects PLI currents. Some of these currents pass through the sensing electrodes, then the electrode cables, and finally via the amplifier input impedances they reach the signal ground. The electrode impedances and the amplifier input impedances form an impedance bridge. Due to electrode impedance instability over time, the bridge tends to be imbalanced and produces differential PLI which is amplified together with the useful signal. This paper describes a powerful mixed analog–digital solution for automatic impedance bridge balance using software PLL for line synchronization. The approach is implemented and validated through recorded real ECG signals. The PLI is canceled by adding part of the common-mode voltage, with automatically adjusted amplitude and phase, to the useful differential biosignal. The described approach produces high-quality biosignals without the need for a common-mode reference electrode. It is applicable to all biosignals taken with surface electrodes like ECG, EEG, EMG, EOG, etc., and can benefit all diagnostic and therapeutic medical devices where these signals are in use.

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References

  1. Reilly R, Lee T (2010) Electrograms (ECG, EEG, EMG, EOG). Technol Health Care 18:443–458

    Article  Google Scholar 

  2. Kaniusas E (2019) Biomedical signals and sensors III. Linking electric biosignals and biomedical sensors. Springer Nature Switzerland AG

  3. Huhta J, Webster J (1973) 60-Hz interference in electrocardiography. IEEE Trans Biomed Eng 20:91–101

    Article  CAS  Google Scholar 

  4. Pallás-Areny R, Colominas J (1991) Simple, fast method for patient body capacitance and power-line electric interference measurement. Med Biol Eng Comput 29:561–563

    Article  Google Scholar 

  5. Winter B, Webster J (1983) Reduction of interference due to common mode voltage in biopotential amplifiers. IEEE Trans Biorned Eng 30:58–62

    Article  CAS  Google Scholar 

  6. Winter B, Webster J (1983) Driven-right-leg circuit design. IEEE Trans Biomed Eng 30:62–66

    Article  CAS  Google Scholar 

  7. Freeman D et al (2015) Saturation of the right-leg drive amplifier in low-voltage ECG monitors. IEEE Trans Biomed Eng 62:323–330

    Article  Google Scholar 

  8. Thakor N, Webster J (1980) Ground-free ECG recording with two electrodes. IEEE Trans Biomed Eng 27:699–704

    Article  CAS  Google Scholar 

  9. Dobrev D, Neycheva T, Mudrov N (2008) Bootstrapped two-electrode biosignal amplifier. Med Biol Eng Comput 46:613–619

    Article  Google Scholar 

  10. Dobrev D, Daskalov I (2002) Two-electrode biopotential amplifier with current-driven inputs. Med Biol Eng Comput 40:122–127

    Article  CAS  Google Scholar 

  11. Hwang I, Webster J (2008) Direct interference canceling for two-electrode biopotential amplifier. IEEE Trans Biomed Eng 55:2620–2627

    Article  Google Scholar 

  12. Levkov C (1989) Fast integer coefficient FIR filters to remove the ac interference and the high-frequency noise. Med Biol Eng Comput 27:330–332

    Article  CAS  Google Scholar 

  13. Tabakov S, Iliev I, Krasteva V (2008) Online digital filter and QRS detector applicable in low resource ECG monitoring systems. Ann Biomed Eng 36:1805–1815

    Article  Google Scholar 

  14. Levkov C, Michov G, Ivanov R, Daskalov I (1984) Subtraction of 50Hz interference from the electrocardiogram. Med Biol Eng Comput 22:371–373

    Article  CAS  Google Scholar 

  15. Christov I, Dotsinsky I (1888) New approach to the digital elimination of 50 Hz interference from the electrocardiogram. Med Biol Eng Comput 26:431–434

    Article  Google Scholar 

  16. Levkov C et al (2005) Removal of power-line interference from the ECG: a review of the subtraction procedure. BioMed Eng OnLine 4:50

    Article  Google Scholar 

  17. Widrow B et al (1975) Adaptive noise canceling: principles and applications. Proc IEEE 63:1692–1716

    Article  Google Scholar 

  18. Tompkins W (1995) Biomedical digital signal processing. Prentice Hall, 174–183

  19. Jekova I et al (2009) Bench study of the accuracy of a commercial AED arrhythmia analysis algorithm in the presence of electromagnetic interference. Physiol Meas 30:695–705

    Article  Google Scholar 

  20. Mortara D (1977) Digital filters for ECG signals. Comp Card, 511–514

  21. Wikipedia the free encyclopedia (2021) Balanced line. Wikimedia Foundation Inc, https://en.wikipedia.org/wiki/Balanced_line

  22. Wikipedia the free encyclopedia (2021) Wheatstone bridge. Wikimedia Foundation Inc, https://en.wikipedia.org/wiki/Wheatstone_bridge

  23. Dobrev D, Neycheva T (2011) Increased power-line interference rejection by adaptive common mode impedance balance. Annu J Electron 5:80–83

    Google Scholar 

  24. Park M, Kita H, Klee M, Oomura Y (1983) Bridge balance in intracellular recording; introduction of the phase-sensitive method. J Neurosci Methods 8:105–125

    Article  CAS  Google Scholar 

  25. Adli YY (1998) Impedance balancing analysis for power-line interference elimination in ECG signal. IEEE Instrument Meas Techn Conf 1:235–238

    Google Scholar 

  26. Negrao J et al (2013) Electromagnetic interference reduction by dynamic impedance balancing applied to biosensors. Braz J Biom Eng 29:269–277

    Google Scholar 

  27. Parente F et al (2018) An analog bootstrapped biosignal read-out circuit with common-mode impedance two-electrode compensation. IEEE Sens J 18:2861–2869

    Article  Google Scholar 

  28. Dobrev D, Neycheva T (2013) Analog approach for common mode impedance balance in two-electrode biosignal amplifiers. Annu J Electron 7:68–71

    Google Scholar 

  29. Dobrev D, Neycheva T (2013) Digital lock-in technique for input impedance balance in two-electrode biosignal amplifiers. Annu J Electron 7:64–67

    Google Scholar 

  30. Dobrev D, Neycheva T (2014) Current driven automatic electrode impedance balance in ground free bosignal acquisition. Annu J Electron 8:62–65

    Google Scholar 

  31. Dobrev D, Neycheva T (2014) Software PLL for power-line interference synchronization: design, modeling and simulation. Annu J Electron 8:58–61

    Google Scholar 

  32. Dobrev D (2015) Software PLL syncs to line using moving-average filter. EDN, https://www.edn.com/software-pll-syncs-to-line-using-moving-average-filter

  33. Dobrev D, Neycheva T (2015) Software PLL for power-line interference synchronization: implementation and results. Annu J Electron 9:18–21

    Google Scholar 

  34. Dobrev D Neycheva T (2016) Automatic common mode electrode-amplifier impedance balance with SPLL synchronization. Proc 25th Int Sci Conf Electron 1–4

  35. Dobrev D Neycheva T (2016) Automatic current driven electrode-amplifier impedance balance with SPLL synchronization. Proc 25th Int Sci Conf Electron 1–4

  36. Dobrev D Neycheva T (2019) Automatic common mode impedance balance: implementation and results. Proc 28th Int Sci Conf Electron 1–4

  37. Dobrev D, Neycheva T (2011) Bootstrapped instrumentation biosignal amplifier. Annu J Electron 5:76–79

    Google Scholar 

  38. Dobrev D, Neycheva T (2012) Simple two-electrode bootstrapped non-differential biosignal amplifier. Annu J Electron 6:8–11

    Google Scholar 

  39. Dobrev D Neycheva T (2021) Software automatic gain control. Proc 30th Int Sci Conf Electron 1–4

  40. Spinelli E et al (2006) A practical approach to electrode-skin impedance unbalance measurement. IEEE Trans Biomed Eng 53:1451–1453

    Article  Google Scholar 

  41. Dotsinsky I Christov I Daskalov I (2002) Twelve-lead electrocardiogram obtained by eight channels. Electrotechnika & Electronica E+E, 1–2:10–12

  42. Dotsinsky I, Christov I, Levkov C, Daskalov I (1985) A microprocessor–electrocardiograph. Med Biol Eng Comp 23:209–212

    Article  CAS  Google Scholar 

  43. Dotsinsky I, Christov I, Daskalov I (1991) Multichannel DC amplifier for a microprocessor electroencephalograph. Med Biol Eng Comp 29:324–329

    Article  CAS  Google Scholar 

  44. Jekova I, Krasteva V (2005) Subtraction of 16.67 Hz railroad net interference from the electrocardiogram: application for automatic external defibrillators. Physiol Meas 26:987–1003

    Article  Google Scholar 

  45. Konopelski P, Ufnal M (2016) Electrocardiography in rats: a comparison to human. Physiol Res 65:717–725

    Article  CAS  Google Scholar 

Download references

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Authors and Affiliations

  1. Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str, Block 105, Sofia, 1113, Bulgaria

    Dobromir P. Dobrev & Tatyana D. Neycheva

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  1. Dobromir P. Dobrev
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  2. Tatyana D. Neycheva
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Correspondence to Dobromir P. Dobrev.

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Dobrev, D.P., Neycheva, T.D. High-quality biopotential acquisition without a reference electrode: power-line interference reduction by adaptive impedance balancing in a mixed analog–digital design. Med Biol Eng Comput 60, 1801–1814 (2022). https://doi.org/10.1007/s11517-022-02586-0

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  • DOI: https://doi.org/10.1007/s11517-022-02586-0

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