Flexible Diamond-Based Sensors for Chemical Sensing

Abstract

Flexible electrochemical sensors have been successfully used to detect a variety of biologically- and environmentally-relevant analytes, including neurotransmitters (NTs) and heavy metals, among others. Other flexible sensing materials (gold, bismuth, printed carbon, etc.) have shown promise, but are typically designed for individual applications. Our boron-doped diamond (BDD)-based flexible sensors offer several advantages including broad applicability, batch fabrication processes, wide potential window, low capacitive background current, and good biocompatibility. In this study, the applicability of the flexible BDD sensors to both NT and heavy metal sensing was investigated. Dopamine (DA), lead (Pb), and copper (Cu) were used as the model analytes. A detailed wafer-transfer process of the BDD film from silicon (Si) to flexible parylene C substrates is described. Through this novel fabrication process, the grown-side of the BDD film is exposed. DA was studied using square wave voltammetry (SWV) as the lone analyte, as well as in solution with ascorbic acid to verify potential inter-ference. Heavy metal analysis of Pb and Cu was performed using anodic stripping voltammetry (ASV) in solutions similar to the pH of human perspiration. The BDD electrode yielded limits of detection (LOD) of 10 and 30 ppb for Pb and Cu, respectively. For Pb and Cu, the calculated LOD (3 min deposition time) is well below values previously re-ported in human perspiration. These flexible (and potentially wearable) grown-side exposed BDD sensors further exemplify the capability and versatility of electroanalytical measurements.