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Pencil traces drawn on print papers are shown to function as strain gauges and chemiresistors. Regular graphite/clay pencils can leave traces composed of percolated networks of fine graphite powders, which exhibit reversible resistance changes upon compressive or tensile deflections. Flexible toy pencils can leave traces that are essentially thin films of graphite/polymer composites, which show reversible changes in resistance upon exposure to volatile organic compounds due to absorption/desorption induced swelling/ recovery of the polymer binders. Pencil-on-paper devices are low-cost, extremely simple and rapid to fabricate. They are light, flexible, portable, disposable, and do not generate potentially negative environmental impact during processing and device fabrication. One can envision many other types of pencil drawn paper electronic devices that can take on a great variety of form factors. Hand drawn devices could be useful in resource-limited or emergency situations. They could also lead to new applications integrating art and electronics. [ABSTRACT FROM AUTHOR]

This study investigates potentiodynamic synthesis of polyaniline (PANI) using pencil graphite electrodes (PGEs), aiming to elucidate deposition mechanisms under simple experimental conditions. By exploring PANI electrosynthesis through electrochemical, spectroscopic, and computational approaches, valuable insights into the physicochemical aspects of aniline polymerization are gained. The proposed synthetic method was challenged for the development of a new molecularly imprinted polymer for chloramphenicol on the surface of PGEs to obtain an innovative impedimetric sensor. The sensing platform shows a linear response in the target concentration range between 0.1 and 17.5 nM, in aqueous solutions, with a limit of detection of 0.03 nM and a limit of quantification of 0.09 nM. The results obtained suggest that the synthesis method proposed provide a way to obtain stable and electroactive polyaniline film with huge potential application. [ABSTRACT FROM AUTHOR]

A disposable nonenzymatic glucose sensor was obtained by pulsed electrodeposition of Pt-CuO on a graphite pencil electrode (GPE). The morphology of the modified GPE was studied using SEM, and the chemical composition of the coating was examined by EDAX and XRD. The electrochemical response of the modified GPE was compared with individual copper- and platinum-modified GPEs. The electrodeposition parameters were optimized with respect to the electrocatalytic activity of the deposits towards glucose oxidation. Best operated at a working potential of 0.6 V vs. Ag/AgCl, the sensor has a sensitivity of 2035 μA mM−1 cm−2, a 0.1 μM detection limit and a wide linear response range that extends up to 25 mM. It is highly selective for glucose in the presence of various exogenous and endogenous interfering species. Eventhough the requirement of alkaline medium for sensing is a limitation, easy fabrication procedure, very high sensitivity and selectivity, wide analytical range, and disposable sensor characteristics show potential application towards blood glucose determination. [ABSTRACT FROM AUTHOR]

Graphite pencil lead (GPL) covered with Au nanodendrites (AuNDs) (the AuND@GPL sensor) has been demonstrated as an electrochemical sensor for simultaneous detection of Pb(II), Cu(II) and Hg(II) in water samples. To meet both the demands of cost-effectiveness and required analytical performance, a cheap GPL was chosen as a sensor platform and AuNDs providing a large electroactive surface area were fabricated on the surface of GPL by a simple electrodeposition in less than one minute. Due to the incorporation of AuNDs, the sensitivities of simultaneous detection of Pb(II), Cu(II) and Hg(II) were improved with a limit of detection below 0.2 ppb, and the peak intensities did not vary significantly even though concentrations of interferants were 100-fold greater. The sensor-to-sensor reproducibility was good (relative standard deviation below 4.6%), which is mainly contributed to the simple one-step electrodeposition for sensor preparation. The overall detection performance was better or similar in comparison with those of previously reported GPL-based sensors. Moreover, when real lake water samples were analyzed, the AuND@GPL sensor was able to accurately determine the Pb(II), Cu(II) and Hg(II) concentrations. The sensor is cost-effective due to the use of GPL as a platform, so it has a strong potential as a disposable electrochemical sensor for at-site water quality monitoring. [ABSTRACT FROM AUTHOR]

The presented study focuses on the optimum conditions for chemical activation of pencil graphite electrodes (PGE) used in the determination of bisphenol A (BPA). The prepared ethanol–HCl mixture for chemical activation of pencil graphite electrode exhibits better activation factor compared with traditional activation methods like anodizing. The obtained porous and highly conductive surface of PGE can be used as a sensing device. The electrochemical behavior of BPA at the modified sensor was investigated. The effects of pH, accumulation time and sensor activation were examined. In the optimum experimental conditions, adsorptive differential pulse voltammetry was used for determination of BPA, which exhibits a linear calibration graph of Ip versus BPA concentration in the range 1.25 × 10–8 to 1.34 × 10–4 M. The calculated detection limit for S/N = 3 was 1.0 nM. The presented sensor is reusable. The activated PGE was applied for the determination of BPA leached from baby bottles as a real sample using spike method. [ABSTRACT FROM AUTHOR]