Review—A Pencil Drawing Overview: From Graphite to Electrochemical Sensors/Biosensors Applications

Abstract

Much effort was made in the literature to put pencil-drawing as an attractive way to fabricate electrochemical sensors. The pencil drawing is one of the easiest, cost-effective, unique single-step methods for fabricating paper-based devices without necessitating any expensive instrumentation by merely transferring the carbon by exfoliation abrasion on paper. Additionally, much has to be done to improve the quality of this transfer carbon to achieve a suitable sensing platform for electrochemical measurements. Hence, this review article aims to bring the new approaches developed in the last five years to circumvent some fabrication problems and enhance this “carbonization” step for electrochemistry detection using paper-based sensors. We will start the discussion on the carbon materials moving to the substrate and finally discuss the strategies to produce the conductive tracks and enhance their properties for sensing applications.

Pencil-drawn graphitic traces on sticky note paper for wearable electronics

“…Increasing the quantity of clay to graphite creates a harder, more durable pencil, whereas increasing graphite content results in a "softer" pencil based on the hardness of the leads. The clay fraction in an H pencil is significantly less than in a 6H pencil lead [12][13][14].…”

Diagnosis of cancer using carbon nanomaterial-based biosensors

“…They can also be easily functionalized due to presence of oxygen-containing active sites on their surfaces 102 . Therefore, functionalization is a very crucial part of utilizing based devices 109 . The other quantitative part is the limit of detection (LOD), defined as the lowest concentration of analyte where the signal to noise ratio is greater than three, a parameter to check the sensor's performance.…”

“…108 In recent years, many techniques have been used to fabricate electrochemical sensors but pencil drawing is one of the attractive, cost-effective and easiest ways for fabricating paper-based devices. 109 The other quantitative part is the limit of detection (LOD), defined as the lowest concentration of analyte where the signal to noise ratio is greater than three, a parameter to check the sensor's performance. In biosensors, selectivity is a crucial part, and depending upon the target material, the bio-recognition element is placed on the electrode element.…”

Dip-coated carbon nanotube surface deposits as stable, effective response enhancers in pencil lead electrode voltammetry

“…[5][6][7][8] PL-based electroanalysis is widely used nowadays, as attested in recent reviews, with uses ranging from environmental, clinical and pharmaceutical testing to food screening. [9][10][11][12][13][14] PL electrodes (PLEs) may be built as embedded disks, like their Pt, Au or GC equivalents, or fabricated with a protruding end that works as a rod-shaped electrode, and several published reports suggest that PLE surface pre-treatment and/or modication with polymers, organic species or nanomaterials enhances their analyte sensitivity and selectivity. Electrochemically activated PLEs detected, for instance, food antioxidants, drugs and neurotransmitters signicantly better than their untreated precursors.…”