IEEE transactions on bio-medical engineering
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IEEE Trans Biomed Eng · Jul 2000
Chronic neural stimulation with thin-film, iridium oxide electrodes.
Experiments were conducted to assess the effect of chronic stimulation on the electrical properties of the electrode-tissue system, as measured using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Silicon, micromachined probes with multiple iridium oxide stimulating electrodes (400-1600 micron 2) were implanted in guinea pig cortex. A 10-17 day post-operative recovery period was followed by five days of monopolar stimulation, two hours/electrode each day using biphasic, constant current stimulation (5-100 microA, 100 microseconds/phase). ⋯ The data and modeling results shows that applying charge to the electrode can consistently reduce the impedance of the electrode-tissue system. Analysis of explanted probes suggests that the interaction between the tissue and electrode is dependent on whether chronic pulses were applied. It is hypothesized that the interface between the tissue and metal is altered by current pulsing, resulting in a temporary impedance shift.
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IEEE Trans Biomed Eng · Jul 2000
Comparative StudyWavelet compression of ECG signals by the set partitioning in hierarchical trees algorithm.
A wavelet electrocardiogram (ECG) data codec based on the set partitioning in hierarchical trees (SPIHT) compression algorithm is proposed in this paper. The SPIHT algorithm [1] has achieved notable success in still image coding. ⋯ Experiments on selected records from the MIT-BIH arrhythmia database revealed that the proposed codec is significantly more efficient in compression and in computation than previously proposed ECG compression schemes. The coder also attains exact bit rate control and generates a bit stream progressive in quality or rate.