title: Highly Stretchable Potentiometric pH Sensor Fabricated via Laser Carbonization and Machining of Carbon-Polyaniline Composite.
abstract: The development of stretchable sensors has recently attracted considerable attention. These sensors have been used in wearable and robotics applications, such as personalized health-monitoring, motion detection, and human-machine interfaces. Herein, we report on a highly stretchable electrochemical pH sensor for wearable point-of-care applications that consists of a pH-sensitive working electrode and a liquid-junction-free reference electrode, in which the stretchable conductive interconnections are fabricated by laser carbonizing and micromachining of a polyimide sheet bonded to an Ecoflex substrate. This method produces highly porous carbonized 2D serpentine traces that are subsequently permeated with polyaniline (PANI) as the conductive filler, binding material, and pH-sensitive membrane. The experimental and simulation results demonstrate that the stretchable serpentine PANI/C-PI interconnections with an optimal trace width of 0.3 mm can withstand elongations of up to 135% and are robust to more than 12 000 stretch-and-release cycles at 20% strain without noticeable change in the resistance. The pH sensor displays a linear sensitivity of -53 mV/pH (r2= 0.976) with stable performance in the physiological range of pH 4-10. The sensor shows excellent stability to applied longitudinal and transverse strains up to 100% in different pH buffer solutions with a minimal deviation of less than ±4 mV. The material biocompatibility is confirmed with NIH 3T3 fibroblast cells via PrestoBlue assays.
authors.forename: Rahim
authors.identifier: http://orcid.org/0000-0001-5302-782X
authors.initials: R
authors.lastname: Rahimi
authors.forename: Manuel
authors.initials: M
authors.lastname: Ochoa
authors.affiliation: Biomaterials Innovation Research Center, School of Electrical and Computer Engineering, Division of Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School , Cambridge, Massachusetts 02139, United States.|Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Ali
authors.initials: A
authors.lastname: Tamayol
authors.affiliation: Biomaterials Innovation Research Center, School of Electrical and Computer Engineering, Division of Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School , Cambridge, Massachusetts 02139, United States.|Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Shahla
authors.initials: S
authors.lastname: Khalili
authors.affiliation: Biomaterials Innovation Research Center, School of Electrical and Computer Engineering, Division of Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School , Cambridge, Massachusetts 02139, United States.|Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.|Department of Bioindustrial Technologies, College of Animal Bioscience and Technology, Konkuk University , Seoul 143-701, Republic of Korea.|Department of Physics, King Abdulaziz University , Jeddah 21569, Saudi Arabia.
authors.forename: Ali
authors.identifier: http://orcid.org/0000-0002-2692-1524
authors.initials: A
authors.lastname: Khademhosseini
authors.forename: Babak
authors.initials: B
authors.lastname: Ziaie
keywords: electrochemical sensors; laser carbonization; porous carbon; stretchable; wearable point-of-care