Poster CC2 - Addressing Health Disparities with Accessible Electrochemical Sensors

Introduction: The increasing cost and limited accessibility of healthcare are pressing issues in both developing and developed nations. Accurate analysis is fundamental to disease diagnosis and treatment management. Developing reliable diagnostics that allow for decentralized and continuous analysis, either at home or at the point of care, is essential for transforming the healthcare landscape. Our strategy to tackle this challenge involves using widely available materials and clean-room-free fabrication methods to create electrochemical sensors. These sensors are designed to be user-friendly, requiring no specialized skills to operate, and can be integrated into common treatment accessories to effectively monitor patient recovery. Our work is primarily focused on developing low-cost electrochemical sensors for addressing disease diagnosis and management for women’s health. Unfortunately, women’s health and needs in this area have been neglected for so long. Developing accessible low-cost tools to improve healthcare access and turnaround time of results can have lasting impact in women’s health.

Materials and

Methods: Silver/silver chloride ink (AGCL-1134) and ink thinner (102-03) were purchased from Kayaku Advanced Materials (Westborough, MA, USA). Electrical-grade Kapton® Polyimide Film (12"×12"×0.005") was obtained from McMaster-Carr, USA. Deionized water (resistivity of 18.20 MΩ/cm) was used for solution preparation. Laser-induced graphene was prepared according to our previous works.1-3 The polyimide (PI) film, with a thickness of 0.005 inches, was washed with acetone, isopropyl alcohol, and deionized (DI) water, then dried at 90 °C for 10 minutes. Next, it was placed in a laser engraver machine (VLS2.30, Universal Laser System Inc.) equipped with a 30 W CO2 laser source operating at a wavelength of 9.3 μm. The electrode pattern, designed using Adobe Illustrator (Adobe, Inc.), was engraved on the PI film in raster mode. After engraving, the electrodes were rinsed again with deionized water and dried at 90 °C for an additional 10 minutes. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) tests were conducted using a CHI 760E (CH Instruments, TX, USA). Wireless in situ measurements were performed with the Sensit BT (PalmSens BV, Utrecht, Netherlands).

Results, Conclusions, and Discussions: The entire electrode system is laser engraved to achieve lost-cost sensors on flexible thin PI film. Here, we produced Laser-induced Graphene (LIG) by converting aromatic polyimide polymer (PI) into 3D, multi-layered, porous graphene structures using a 9.3 μm CO2 laser beam. The quality of LIG, along with its physical, chemical, structural, and electrochemical properties, is highly dependent on the energy surface density (or laser fluence) of the laser beam applied to the PI film during processing. Through optimization of the lasing parameters, we achieved highly stable carbon electrodes with conductivities of less than 25 Ohm per square, and high electrochemical surface area (2-5 times the geometric area). These electrodes were then modified with various receptors such as sensing membranes, charged polymers, or antibodies to achieve selectivity for different biomarkers that are important for women’s health. Specifically, we are monitoring biogenic amines and inflammatory markers in self-collected swabs to identify infections, and we are measuring medications and biomarkers of infection human breast milk. We have demonstrated accurate analysis (less than 10% error) in point-of-care measurements with these modified LIG electrodes. Accessible LIG electrodes are developed to address diagnostics for women’s health. These tools offer accurate analysis at home and at the point of care and facilitate rapid access to results. Future work will focus on developing wearable systems and compact electrical detectors to accompany the LIG-based point-of-care sensors.

Acknowledgements (Optional): We thank USC's Women in Science and Engineering for providing seed funding for this project.