Flexible Inkjet Printed Gold based Electrochemical Sensor for Aqueous Lead Detection Annatoma Arif and Robert C. Roberts Department of Electrical and Computer Engineering, University of Texas at El Paso, El Paso, USA aarif@miners.utep.edu Abstract—This work presents a novel simple, flexible, cost- effective, sensitive, and disposable inkjet printed (IP) electrochemical sensor on PPG Teslin SP600 substrate for aqueous lead (II) detection. The electrochemical cell contains a gold (Au) working electrode (WE), Au counter electrode (CE), and integrated silver chloride (AgCl) reference electrode (RE). The lateral dimension and area of the fabricated inkjet printed flexible (IPF) electrochemical sensor are 12×8×0.52 mm 3 and 3.41 mm 2 respectively. The reported sensor is initially IP using silver (Ag) nanoparticle conductive ink. The Au WE and CE are obtained with 24K brush Au-plating technology. AgCl formation occurred with dilute sodium hypochlorite (3%) immersion of the sintered Ag RE. The electrochemical sensor is characterized with 3mM of lead (II) contaminated optimized drinking water (0.1 M HCl). The fabricated novel IPF sensor is further utilized for 14.4 µg/L lead (II) contaminated optimized drinking water which is below the United States Environmental Protection Agency approved lead (II) level in the drinking water – 15 µg/L. The fabrication and characteristics/performance of the IPF electrochemical sensor were analyzed using scanning electron micrograph (SEM) images/ energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV) electrochemical analyses respectively. Keywords—cyclic voltammetry; electrochemical analyses; electrochemical sensor; flexible sensor; inkjet printing; I. INTRODUCTION Heavy metal ions (HMIs) are extremely poisonous for human and environment. It accumulates over the period of time. Once it enters in the system, it never goes away or stops invading the systems. Out of all the HMIs, lead (II) is extremely harmful for human, plant, and water sources. It is a major public health concern which has an extreme adverse effect on human and specifically children. The presence of lead (II) ion in the human blood stream causes severe damage to central nervous system (CNS) and peripheral nervous system (PNS) [1]. It has significant detrimental impacts on children such as learning and behavioral delay, hearing and speech disorder, and attention deficiency [2,3]. Therefore, it is extremely important to have a reliable and consistent method/technology for lead (II) detection in the drinking water. The traditional methods for HMIs detection are atomic absorption spectroscopy (AAS), ultraviolet and visible spectrometry, atomic fluorescence spectroscopy (AFS), and inductively coupled plasma mass spectrometry (ICP- MS) [4]. These available conventional methods are reliable but bulky, expensive, and time-consuming [5]. Hence, a lot of researches are going on around the electrochemical methods for HMIs detection. This method is reliable, cost-effective, sensitive, and consistent. The electrochemical stripping method Fig. 1. Inkjet printed flexible (IPF) electrochemical sensor with gold (Au) working electrode, Au counter electrode, and silver chloride (AgCl) reference electrode. requires chemically modified electrodes for high sensitivity, low response time, and high selectivity. Gold (Au) electrodes play an important role in case of HMIs detection [6]. The available and widely preferred electrode fabrication process in today’s market is screen printing [5,6]. The screen printed electrodes (SPE) are popular due to its cost-effectivity and high reproducibility [7]. However, the performance of SPEs are not reliable and consistent in case of batch to batch fabrication and variety of materials [7]. Consequently, researchers are currently focusing on inkjet printing additive manufacturing technology for sensor fabrication [8,9,10]. This technology offers high resolution, cost-effectivity, low material waste, design flexibility, and multi-material characteristics. Flexibility in case of sensor fabrication is considered as progressive and potential for designing wearable, portable, and cost-effective sensors [11, 12,13]. Hence, this article represents a novel simple, flexible, cost-effective, sensitive, and disposable inkjet printed (IP) Au- based electrochemical sensor on Teslin SP600 for the first time for lead (II) detection in aqueous solution. Fig. 1 represents the fabricated inkjet printed flexible (IPF) Au-based electrochemical sensor with lateral dimension 12×8×0.52 mm 3 and working electrode surface area 3.41 mm 2 . The scanning electron micrograph (SEM) image of the fabricated IPF electrochemical sensor is also shown in Fig. 1. Section II illustrates the fabrication of the IPF electrochemical sensor in detail, section III discusses about the electrochemical analysis i.e. cyclic voltammetry (CV) for characterization and performance evaluation of the fabricated IPF electrochemical sensor for aqueous lead (II) detection, and section IV concludes the summary and future work to improve the performance of the fabricated electrochemical sensor in a descriptive manner. 978-1-6654-4273-2/22/$31.00 ©2022 IEEE 2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) | 978-1-6654-4273-2/22/$31.00 ©2022 IEEE | DOI: 10.1109/FLEPS53764.2022.9781482