Growth of CNT array for physiological monitoring applications

Radhakrishnan, J.; Bhusan, H.; Pandian, P. S.; Rao, K.U. Bhasker; Padaki, V. C.; Aatre, Kiran R.; Xie, Jining; Abraham, Jose K.; Varadan, Vijay K.

doi:10.1117/12.798231

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Using CNT as an array/forest on the surface of the electrode improved electrical contact by allowing penetration of the outer layers of the skin (stratum corneum). However, they are limited as they cannot form good contacts through skin pores and hairs as CNTs are uniformly grown on the substrate without any gaps [38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Characterization of a Novel Polypyrrole (PPy) Conductive Polymer Coated Patterned Vertical CNT (pvCNT) Dry ECG Electrode

Abu-Saude

Morshed

2018

Chemosensors

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Conventional electrode-based technologies, such as the electrocardiogram (ECG), capture physiological signals using an electrolyte solution or gel that evaporates shortly after exposure, resulting in a decrease in the quality of the signal. Previously, we reported a novel dry impedimetric electrode using patterned vertically-aligned Carbon NanoTubes (pvCNT) for biopotential measurement applications. The mechanical adhesion strength of the pvCNT electrode to the substrate was weak, hence, we have improved this electrode using a thin coating of the conductive polymer polypyrrole (PPy) that strengthens its mechanical properties. Multiwall CNTs were grown vertically on a circular stainless-steel disc (⌀ = 10 mm) substrate of 50 µm thickness forming patterned pillars on a square base (100 µm × 100 µm) with an inter-pillar spacing of 200 µm and height up to 1.5 mm. The PPy coating procedure involves applying 10 µL of PPy mixed with 70% ethyl alcohol solution and rapid drying at 300 °C using a hot air gun at a distance of 10 cm. A comparative study demonstrated that the coated pvCNT had higher impedance compared to a non-coated pvCNT but lower impedance compared to the standard gel electrode. The PPy-coated pvCNT had comparable signal capture quality but stronger mechanical adhesion to the substrate.

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Section: Introductionmentioning

confidence: 99%

Characterization of a Novel Polypyrrole (PPy) Conductive Polymer Coated Patterned Vertical CNT (pvCNT) Dry ECG Electrode

Abu-Saude

Morshed

2018

Chemosensors

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“…CNT based biosensors are shown to be biosafe at low concentration external to the body [12,13]. Previous attempts for CNT dry electrodes [14][15][16][17][18][19] had limited success, primarily due to: (1) CNTs were not patterned in those electrodes resulting in a dense surface of CNT tips, and (2) the height of the carbon nanotubes was small (tens of µm range). We have developed a patterned vertical CNT (pvCNT) for dry impedimetric sensing.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of patterned vertical CNT for dry electrode sensing of physiological parameters

Abu-Saude

Consul-Pacareu

Morshed

2015

2015 IEEE Topical Conference on Biomedical Wireless Technologies, Networks, and Sensing Systems (BioWireleSS)

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Dry electrodes for impedimetric sensing of physiological parameters (such as ECG, EEG, and GSR) promise the ability for long duration monitoring. This paper describes the feasibility of a novel dry electrode interfacing using Patterned Vertical Carbon Nanotube (pvCNT) for physiological parameter sensing. The electrodes were fabricated on circular discs (φ = 10 mm) stainless steel substrate. Multiwalled electrically conductive carbon nanotubes were grown in pattered pillar formation of 100 µm squared with 50, 100, 200 and 500µm spacing. The heights of the pillars were between 1 to 1.5 mm. A comparative test with commercial ECG electrodes shows that pvCNT has lower electrical impedance, stable impedance over very long time, and comparable signal capture in vitro. Long duration study shows minimal degradation of impedance over 2 days period. The results demonstrate the feasibility of using pvCNT dry electrodes for physiological parameter sensing.

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A Novel, Needle-Array Dry-Electrode With Stainless Steel Micro-Tips, for Electroencephalography Monitoring

Radhakrishnan¹,

Nithila

Sonawane

et al. 2018

Journal of Medical Devices

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A novel, needle array dry electrode consisting of 10 × 10 array of stainless steel (SS) Microtips was developed for electroencephalography (EEG) monitoring. The developed dry electrode uses commercially available, inexpensive, SS acupuncture needles certified for invasive use, to collect the EEG signal. The microtips of the acupuncture needles project out of a flat Teflon base by approximately 150 μm. Mechanical failure analysis was carried out, with theoretical calculations for individual needles and experimental measurements with a universal testing machine (UTM). The theoretically calculated critical load for failure for individual needle was 0.88 N, while the UTM measurements show the failure occurring at 0.95 N; this difference is probably due to the simplified assumptions used in calculations. The UTM measurements of the individual needle applied against a Silicone elastomer reveal that the force required for the penetration of the needle of the electrode into skin maybe as low as 0.01 N. Needle array insertion into silicone elastomer sheet and its optical inspection was carried out to assess the ability of the microneedles to penetrate the skin. The impedance of the electrode, measured in three electrode configuration in 0.9% NaCl solution, was approximately 6.8KΩ at 20 Hz, which is sufficiently low to fulfill the requirements of biopotential measurement. The construction and characteristics of the developed needle array dry electrode show that they are suitable for penetrating the stratum corneum of the skin and acquire the EEG signal directly from the interstitial fluidic layer underneath. The construction of the electrode and its mechanical and electrical characteristics show that it is a promising dry electrode for long duration EEG Monitoring.

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Growth of CNT array for physiological monitoring applications

Cited by 3 publications

References 5 publications

Characterization of a Novel Polypyrrole (PPy) Conductive Polymer Coated Patterned Vertical CNT (pvCNT) Dry ECG Electrode

Characterization of a Novel Polypyrrole (PPy) Conductive Polymer Coated Patterned Vertical CNT (pvCNT) Dry ECG Electrode

Feasibility of patterned vertical CNT for dry electrode sensing of physiological parameters

A Novel, Needle-Array Dry-Electrode With Stainless Steel Micro-Tips, for Electroencephalography Monitoring

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