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Yao L, Khan SR, Dolmans G, Romme J, Mitra S. High Accuracy Localization for Miniature Ingestible Devices Using Mutual Inductance. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2024; 18:662-678. [PMID: 38306262 DOI: 10.1109/tbcas.2024.3361045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
This article demonstrates an inductively coupled high-accuracy localization system for miniature ingestible devices. It utilizes an inductance double capacitances-series capacitance (LCC-S) compensation architecture that enables mutual inductance measurement at primary side that is positioned outside the human body and less constrained by power budget and size than the miniature ingestible. Depending on the secondary circuit architecture, only limited and simple cooperative measurements are needed from the ingestible secondary side, which saves power and area in the miniature device. The errors in the system are modeled thoroughly, providing insights about system require-ments for a particular localization accuracy target for efficient design and to identify key building blocks with large influence on overall performance. The model shows that sub-centimeter localization root-mean-square error (RMSE) can be achieved with a modest external ADC (18bit) using three primary coils and three secondary coils. The localization is verified along a complete small intestine tract with realistic dimensions. The proposed model is verified by simulation and experiment showing that at the selected frequency range up to 5 MHz the body has no influence on the accuracy. The use of 0.9% saline as phantom is proposed which guarantees the analysis validity for all body types.
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Stine JM, Ruland KL, Beardslee LA, Levy JA, Abianeh H, Botasini S, Pasricha PJ, Ghodssi R. Miniaturized Capsule System Toward Real-Time Electrochemical Detection of H 2 S in the Gastrointestinal Tract. Adv Healthc Mater 2024; 13:e2302897. [PMID: 38035728 DOI: 10.1002/adhm.202302897] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/20/2023] [Indexed: 12/02/2023]
Abstract
Hydrogen sulfide (H2 S) is a gaseous inflammatory mediator and important signaling molecule for maintaining gastrointestinal (GI) homeostasis. Excess intraluminal H2 S in the GI tract has been implicated in inflammatory bowel disease and neurodegenerative disorders; however, the role of H2 S in disease pathogenesis and progression is unclear. Herein, an electrochemical gas-sensing ingestible capsule is developed to enable real-time, wireless amperometric measurement of H2 S in GI conditions. A gold (Au) three-electrode sensor is modified with a Nafion solid-polymer electrolyte (Nafion-Au) to enhance selectivity toward H2 S in humid environments. The Nafion-Au sensor-integrated capsule shows a linear current response in H2 S concentration ranging from 0.21 to 4.5 ppm (R2 = 0.954) with a normalized sensitivity of 12.4% ppm-1 when evaluated in a benchtop setting. The sensor proves highly selective toward H2 S in the presence of known interferent gases, such as hydrogen (H2 ), with a selectivity ratio of H2 S:H2 = 1340, as well as toward methane (CH4 ) and carbon dioxide (CO2 ). The packaged capsule demonstrates reliable wireless communication through abdominal tissue analogues, comparable to GI dielectric properties. Also, an assessment of sensor drift and threshold-based notification is investigated, showing potential for in vivo application. Thus, the developed H2 S capsule platform provides an analytical tool to uncover the complex biology-modulating effects of intraluminal H2 S.
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Affiliation(s)
- Justin M Stine
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD, 20742, USA
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
- Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, 20742, USA
| | - Katie L Ruland
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD, 20742, USA
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
- Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, 20742, USA
| | - Luke A Beardslee
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
| | - Joshua A Levy
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
- Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, 20742, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Hossein Abianeh
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Santiago Botasini
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
| | - Pankaj J Pasricha
- Department of Internal Medicine, Mayo Clinic Hospital, Phoenix, AZ, 85054, USA
| | - Reza Ghodssi
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD, 20742, USA
- Institute for Systems Research, University of Maryland, College Park, MD, 20742, USA
- Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, 20742, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742, USA
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