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Article ; Online: Smart needle to diagnose metastatic lymph node using electrical impedance spectroscopy.

Hong, Yong Tae / Yun, Joho / Lee, Jong Hyun / Hong, Ki-Hwan

2020 Volume 48, Issue 2, Page(s) 281–287

Abstract: Objectives: The cause of cervical lymphadenopathy varies from inflammation to malignancy. Accurate and prompt diagnosis is crucial as delayed detection of malignant lymph node can lead to a worse prognosis. To improve the diagnostic accuracy of ... ...

Abstract	Objectives: The cause of cervical lymphadenopathy varies from inflammation to malignancy. Accurate and prompt diagnosis is crucial as delayed detection of malignant lymph node can lead to a worse prognosis. To improve the diagnostic accuracy of metastatic lymph node, electrical spectroscopy was employed to study human normal and metastatic lymph nodes using a hypodermic needle with fine interdigitated electrodes on its tip (EoN). Subjects and methods: The electrical impedance of samples collected from 8 patients were analyzed in the sweeping frequency range from 1 Hz to 1 MHz. To align the impedance level data of the patients, normalized impedance was employed. Results: The optimal frequency exhibiting the best discrimination results between the normal and cancerous tissues was introduced based on a discrimination index. A high sensitivity (86.2%) and specificity (88.9%) were obtained, which implied that the EoN holds the potential to improve the in vivo diagnostic accuracy of metastatic lymph node during biopsy and surgery. Conclusion: EoN has a promising potential to be utilized in real-time in actual clinical trials without a need for any pre/post-treatment during FNA or surgery. We believe that the EoN could reduce unnecessary operations with its associated morbidity.
MeSH term(s)	Biopsy, Needle/instrumentation ; Biopsy, Needle/methods ; Dielectric Spectroscopy ; Electrodes ; Humans ; Lymph Nodes/pathology ; Lymphatic Metastasis/diagnosis ; Lymphatic Metastasis/pathology ; Reference Values ; Sensitivity and Specificity
Language	English
Publishing date	2020-12-04
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	604552-2
ISSN	1879-1476 ; 0385-8146
ISSN (online)	1879-1476
ISSN	0385-8146
DOI	10.1016/j.anl.2020.08.011
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Fabrication of Fine Electrodes on the Tip of Hypodermic Needle Using Photoresist Spray Coating and Flexible Photomask for Biomedical Applications.

Yun, Joho / Kim, Jinhwan / Lee, Jong-Hyun

Journal of visualized experiments : JoVE

2017 , Issue 129

Abstract: We have introduced a fabrication method for electrical impedance spectroscopy (EIS)-on-a-needle (EoN: EIS-on-a-needle) to locate target tissues in the body by measuring and analyzing differences in the electrical impedance between dissimilar biotissues. ... ...

Abstract	We have introduced a fabrication method for electrical impedance spectroscopy (EIS)-on-a-needle (EoN: EIS-on-a-needle) to locate target tissues in the body by measuring and analyzing differences in the electrical impedance between dissimilar biotissues. This paper describes the fabrication method of fine interdigitated electrodes (IDEs) at the tip of a hypodermic needle using a photoresist spray coating and flexible film photomask in the photolithography process. A polyethylene terephthalate (PET) heat shrink tube (HST) with a wall thickness of 25 µm is employed as the insulation and passivation layer. The PET HST shows a higher mechanical durability compared with poly(p-xylylene) polymers, which have been widely used as a dielectric coating material. Furthermore, the HST shows good chemical resistance to most acids and bases, which is advantageous for limiting chemical damage to the EoN. The use of the EoN is especially preferred for the characterization of chemicals/biomaterials or fabrication using acidic/basic chemicals. The fabricated gap and width of the IDEs are as small as 20 µm, and the overall width and length of the IDEs are 400 µm and 860 µm, respectively. The fabrication margin from the tip (distance between the tip of hypodermic needle and starting point of the IDEs) of the hypodermic needle is as small as 680 µm, which indicates that unnecessarily excessive invasion into biotissues can be avoided during the electrical impedance measurement. The EoN has a high potential for clinical use, such as for thyroid biopsies and anesthesia drug delivery in a spinal space. Further, even in surgery that involves the partial resection of tumors, the EoN can be employed to preserve as much normal tissue as possible by detecting the surgical margin (normal tissue that is removed with the surgical excision of a tumor) between the normal and lesion tissues.
MeSH term(s)	Biomedical Technology/instrumentation ; Biomedical Technology/methods ; Electric Impedance ; Electrodes ; Needles
Language	English
Publishing date	2017-11-28
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Video-Audio Media
ZDB-ID	2259946-0
ISSN	1940-087X ; 1940-087X
ISSN (online)	1940-087X
ISSN	1940-087X
DOI	10.3791/56622
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Facile fabrication of ZnO nanowire memory device based on chemically-treated surface defects.

Park, Woojin / Kim, Tae Hyeon / Nam, Jae Hyeon / Jang, Hye Yeon / Pak, Yusin / Min, Jung-Wook / Yun, Joho / Cho, Byungjin

Nanotechnology

2019 Volume 30, Issue 15, Page(s) 155201

Abstract: In this study, we demonstrate a transistor-type ZnO nanowire (NW) memory device based on the surface defect states of a rough ZnO NW, which is obtained by introducing facile ... ...

Abstract	In this study, we demonstrate a transistor-type ZnO nanowire (NW) memory device based on the surface defect states of a rough ZnO NW, which is obtained by introducing facile H
Language	English
Publishing date	2019-01-17
Publishing country	England
Document type	Journal Article
ZDB-ID	1362365-5
ISSN	1361-6528 ; 0957-4484
ISSN (online)	1361-6528
ISSN	0957-4484
DOI	10.1088/1361-6528/aaff74
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Article: Fabrication of fine electrodes on the tip of hypodermic needle using photoresist spray coating and flexible photomask for biomedical applications

Yun, Joho / Kim, Jinhwan / Lee, Jong-Hyun

Journal of visualized experiments. 2017 Nov. 28, , no. 129

2017

Abstract	We have introduced a fabrication method for electrical impedance spectroscopy (EIS)-on-a-needle (EoN: EIS-on-a-needle) to locate target tissues in the body by measuring and analyzing differences in the electrical impedance between dissimilar biotissues. This paper describes the fabrication method of fine interdigitated electrodes (IDEs) at the tip of a hypodermic needle using a photoresist spray coating and flexible film photomask in the photolithography process. A polyethylene terephthalate (PET) heat shrink tube (HST) with a wall thickness of 25 μm is employed as the insulation and passivation layer. The PET HST shows a higher mechanical durability compared with poly(p-xylylene) polymers, which have been widely used as a dielectric coating material. Furthermore, the HST shows good chemical resistance to most acids and bases, which is advantageous for limiting chemical damage to the EoN. The use of the EoN is especially preferred for the characterization of chemicals/biomaterials or fabrication using acidic/basic chemicals. The fabricated gap and width of the IDEs are as small as 20 μm, and the overall width and length of the IDEs are 400 μm and 860 μm, respectively. The fabrication margin from the tip (distance between the tip of hypodermic needle and starting point of the IDEs) of the hypodermic needle is as small as 680 μm, which indicates that unnecessarily excessive invasion into biotissues can be avoided during the electrical impedance measurement. The EoN has a high potential for clinical use, such as for thyroid biopsies and anesthesia drug delivery in a spinal space. Further, even in surgery that involves the partial resection of tumors, the EoN can be employed to preserve as much normal tissue as possible by detecting the surgical margin (normal tissue that is removed with the surgical excision of a tumor) between the normal and lesion tissues.
Keywords	acids ; anesthesia ; biocompatible materials ; biological resistance ; biopsy ; chemical bases ; coatings ; dielectric spectroscopy ; drugs ; durability ; electric impedance ; electrodes ; excision ; heat ; insulating materials ; neoplasms ; polyethylene terephthalates ; resection ; tissues
Language	English
Dates of publication	2017-1128
Size	p. e56622.
Publishing place	Journal of Visualized Experiments
Document type	Article
ZDB-ID	2259946-0
ISSN	1940-087X
ISSN	1940-087X
DOI	10.3791/56622
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Improvement of Depth Profiling into Biotissues Using Micro Electrical Impedance Spectroscopy on a Needle with Selective Passivation.

Yun, Joho / Kim, Hyeon Woo / Lee, Jong-Hyun

Sensors (Basel, Switzerland)

2016 Volume 16, Issue 12

Abstract: A micro electrical impedance spectroscopy (EIS)-on-a-needle for depth profiling (μEoN-DP) with a selective passivation layer (SPL) on a hypodermic needle was recently fabricated to measure the electrical impedance of biotissues along with the penetration ...

Abstract	A micro electrical impedance spectroscopy (EIS)-on-a-needle for depth profiling (μEoN-DP) with a selective passivation layer (SPL) on a hypodermic needle was recently fabricated to measure the electrical impedance of biotissues along with the penetration depths. The SPL of the μEoN-DP enabled the sensing interdigitated electrodes (IDEs) to contribute predominantly to the measurement by reducing the relative influence of the connection lines on the sensor output. The discrimination capability of the μEoN-DP was verified using phosphate-buffered saline (PBS) at various concentration levels. The resistance and capacitance extracted through curve fitting were similar to those theoretically estimated based on the mixing ratio of PBS and deionized water; the maximum discrepancies were 8.02% and 1.85%, respectively. Depth profiling was conducted using four-layered porcine tissue to verify the effectiveness of the discrimination capability of the μEoN-DP. The magnitude and phase between dissimilar porcine tissues (fat and muscle) were clearly discriminated at the optimal frequency of 1 MHz. Two kinds of simulations, one with SPL and the other with complete passivation layer (CPL), were performed, and it was verified that the SPL was advantageous over CPL in the discrimination of biotissues in terms of sensor output.
Language	English
Publishing date	2016-12-21
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2052857-7
ISSN	1424-8220 ; 1424-8220
ISSN (online)	1424-8220
ISSN	1424-8220
DOI	10.3390/s16122207
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Detection of ischemic changes in the vascular endothelial cell layer by using microelectrochemical impedance spectroscopy.

Cha, Jung-Joon / Kim, Jinhwan / Yun, Joho / Park, Yangkyu / Lee, Jong-Hyun

Medical engineering & physics

2018 Volume 62, Page(s) 58–62

Abstract: Endothelial cells have many important roles in the cardiovascular system, such as controlling vasomotor actions and hemostasis. In the event of endothelial cell dysfunction, the risk of cardiovascular disease increases. Therefore, the objective of this ... ...

Abstract	Endothelial cells have many important roles in the cardiovascular system, such as controlling vasomotor actions and hemostasis. In the event of endothelial cell dysfunction, the risk of cardiovascular disease increases. Therefore, the objective of this study was to investigate the early detection and diagnosis of endothelial cell dysfunction. Injury and restoration in vascular endothelial cells exposed to ischemic stress may affect changes in the electrical impedance. We measured the status of the endothelial cell layer by using microelectrochemical impedance spectroscopy. We used cultured rat primary vascular endothelial cells to measure the electrical impedance under different conditions (control, ischemia, and recovery). Our results revealed that the electrical impedance in vascular endothelial cells under different conditions has quantitatively distinct values. At the optimal frequency, the real parts (Z
MeSH term(s)	Animals ; Dielectric Spectroscopy/instrumentation ; Electrochemistry ; Endothelial Cells/pathology ; Equipment Design ; Ischemia/diagnosis ; Ischemia/pathology ; Microtechnology/instrumentation ; Rats
Language	English
Publishing date	2018-10-11
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	1181080-4
ISSN	1873-4030 ; 1350-4533
ISSN (online)	1873-4030
ISSN	1350-4533
DOI	10.1016/j.medengphy.2018.09.005
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Zs.B 2231: Show issues

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Article ; Online: Evaluation of Electrical Impedance Spectroscopy-on-a-Needle as a Novel Tool to Determine Optimal Surgical Margin in Partial Nephrectomy.

Kim, Hyeon Woo / Yun, Joho / Lee, Jeong Zoo / Shin, Dong Gil / Lee, Jong-Hyun

Advanced healthcare materials

2017 Volume 6, Issue 18

Abstract: A hypodermic needle has been introduced incorporating an electrical impedance spectroscopy (EIS) sensor, called micro-EIS-on-a-needle for depth profiling (μEoN-DP). The μEoN-DP can locate endophytic renal tumors as well as determine tumor margins by ... ...

Abstract	A hypodermic needle has been introduced incorporating an electrical impedance spectroscopy (EIS) sensor, called micro-EIS-on-a-needle for depth profiling (μEoN-DP). The μEoN-DP can locate endophytic renal tumors as well as determine tumor margins by detecting the impedance difference between normal and cancer tissues. To evaluate the μEoN-DP as a novel tool to determine the optimal surgical margin during partial nephrectomy (PN), the electrical impedance differences between renal parenchymal tissues and renal cell carcinoma (RCC) tumors are investigated with regard to the distance from the tumors. Optimal frequencies at which the discrimination extent is maximized are suggested based on the discrimination index. The resistance and capacitance of normal and cancer tissues are extracted using electrical equivalent circuit by excluding the influences of other electrical components on the sensor output. The extracted resistance and capacitance of cancer tissues are 37.8% larger and 25.7% smaller than that of normal tissues, respectively. Additionally, high sensitivity and specificity are obtained by using extracted resistance and capacitance, thus implying that the μEoN-DP shows promise as a supplementary tool for PN margin evaluation and decreasing the prevalence of positive surgical margins while maximizing parenchymal preservation.
Language	English
Publishing date	2017-09
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2649576-4
ISSN	2192-2659 ; 2192-2640
ISSN (online)	2192-2659
ISSN	2192-2640
DOI	10.1002/adhm.201700356
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Zs.A 6966: Show issues

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Article ; Online: Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines

Yangkyu Park / Hyeon Woo Kim / Joho Yun / Seungwan Seo / Chang-Ju Park / Jeong Zoo Lee / Jong-Hyun Lee

BioMed Research International, Vol

Real-Time Electrical Impedance Measurement at an Optimal Frequency

2016 Volume 2016

Abstract: Purpose. To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and Methods. Two types of μEIS devices were designed and used in combination to measure ... ...

Abstract	Purpose. To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and Methods. Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF) was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT) was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results. The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p<0.001), was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p<0.001). Conclusion. The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF.
Keywords	Medicine (General) ; R5-920 ; Medicine ; R
Subject code	621
Language	English
Publishing date	2016-01-01T00:00:00Z
Publisher	Hindawi Publishing Corporation
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines: Real-Time Electrical Impedance Measurement at an Optimal Frequency.

Park, Yangkyu / Kim, Hyeon Woo / Yun, Joho / Seo, Seungwan / Park, Chang-Ju / Lee, Jeong Zoo / Lee, Jong-Hyun

BioMed research international

2016 Volume 2016, Page(s) 8748023

Abstract: Purpose: To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS).: Materials and methods: Two types of μEIS devices were designed and used in combination to ... ...

Abstract	Purpose: To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and methods: Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF) was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT) was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results: The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p < 0.001), was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p < 0.001). Conclusion: The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF.
MeSH term(s)	Cell Line, Tumor ; Dielectric Spectroscopy ; Humans ; Neoplasms, Glandular and Epithelial/metabolism ; Neoplasms, Glandular and Epithelial/pathology ; Urothelium/metabolism ; Urothelium/pathology
Language	English
Publishing date	2016
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2698540-8
ISSN	2314-6141 ; 2314-6133
ISSN (online)	2314-6141
ISSN	2314-6133
DOI	10.1155/2016/8748023
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Micro electrical impedance spectroscopy on a needle for ex vivo discrimination between human normal and cancer renal tissues.

Yun, Joho / Kim, Hyeon Woo / Park, Yangkyu / Cha, Jung-Joon / Lee, Jeong Zoo / Shin, Dong Gil / Lee, Jong-Hyun

Biomicrofluidics

2016 Volume 10, Issue 3, Page(s) 34109

Abstract: The ex-vivo discrimination between human normal and cancer renal tissues was confirmed using μEoN (micro electrical impedance spectroscopy-on-a-needle) by measuring and comparing the electrical impedances in the frequency domain. To quantify the extent ... ...

Abstract	The ex-vivo discrimination between human normal and cancer renal tissues was confirmed using μEoN (micro electrical impedance spectroscopy-on-a-needle) by measuring and comparing the electrical impedances in the frequency domain. To quantify the extent of discrimination between dissimilar tissues and to determine the optimal frequency at which the discrimination capability is at a maximum, discrimination index (DI) was employed for both magnitude and phase. The highest values of DI for the magnitude and phase were 5.15 at 1 MHz and 3.57 at 1 kHz, respectively. The mean magnitude and phase measured at the optimal frequency for normal tissues were 5013.40 ± 94.39 Ω and -68.54 ± 0.72°, respectively; those for cancer tissues were 4165.19 ± 70.32 Ω and -64.10 ± 0.52°, respectively. A statistically significant difference (p< 0.05) between the two tissues was observed at all the investigated frequencies. To extract the electrical properties (resistance and capacitance) of these bio-tissues through curve fitting with experimental results, an equivalent circuit was proposed based on the μEoN structure on the condition that the μEoN was immersed in the bio-tissues. The average and standard deviation of the extracted resistance and capacitance for the normal tissues were 6.22 ± 0.24 kΩ and 280.21 ± 32.25 pF, respectively, and those for the cancer tissues were 5.45 ± 0.22 kΩ and 376.32 ± 34.14 pF, respectively. The electrical impedance was higher in the normal tissues compared with the cancer tissues. The μEoN could clearly discriminate between normal and cancer tissues by comparing the results at the optimal frequency (magnitude and phase) and those of the curve fitting (extracted resistance and capacitance).
Language	English
Publishing date	2016-05-19
Publishing country	United States
Document type	Journal Article
ISSN	1932-1058
ISSN	1932-1058
DOI	10.1063/1.4951702
Database	MEDical Literature Analysis and Retrieval System OnLINE

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