A Miniature pH Sensor in a Subcutaneous Injection Needle for Biofluid Sensing

The pH value in bodily fluids is a crucial diagnostic marker. Conventional glass-rod pH sensors display reliability in aqueous solutions, but the pH-sensitive glass membrane makes them prone to inaccuracies in viscous solutions due to elevated junction potentials and bulky design hinders miniaturiza...

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Bibliographic Details
Published in:IEEE sensors letters 2024-10, Vol.8 (10), p.1-4
Main Authors: Chawang, Khengdauliu, Bing, Sen, Stellar, Jon, Chiao, J.-C.
Format: Article
Language:English
Subjects:
Aqueous solutions
biofluid
Body fluids
Buffer solutions
Cost effectiveness
Displays
Electric potential
Electrodes
flexible
Fluids
In vivo methods and tests
Iridium
iridium oxide (IrO<named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX"> _x</tex-math> </inline-formula> </named-content>)
miniature
Miniaturization
Needles
pH sensor
Polyimides
printable back-to-back (b2b)
Reliability
Sensitivity
Sensor phenomena
Sensors
Silver chloride
Substrates
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Summary:The pH value in bodily fluids is a crucial diagnostic marker. Conventional glass-rod pH sensors display reliability in aqueous solutions, but the pH-sensitive glass membrane makes them prone to inaccuracies in viscous solutions due to elevated junction potentials and bulky design hinders miniaturization. To overcome this issue, this work introduces a new pH sensor design and fabrication that enables miniaturization and reliability in aqueous and viscous solutions and facilitates insertion into a needle for in vivo monitoring. Utilizing a printing technique for the application of iridium oxide (IrOx) and silver/silver chloride coating on a single flexible polyimide substrate offers cost-effectiveness and production scalability. The sensor then is tailored with a sharp blade to a narrow strip that fits into a 20-gauge needle. The electrochemical measurements demonstrate that electrodes produced through this method demonstrate an accuracy of up to 0.1 pH within a narrow pH range (7.35-7.45) in buffer solutions and real human serum tests.
ISSN:2475-1472
2475-1472
DOI:10.1109/LSENS.2024.3454486