Ultraflexible Screen‐Printed Graphitic Electroanalytical Sensing Platforms

Abstract

The pursuit of ultraflexible sensors has arisen from the recent implementation of electrochemical sensors into wearable clothing where extensive mechanical stress upon the sensing platform is likely to occur. Such scenarios have witnessed screen‐printed electrodes being incorporated into the waistband of undergarments for the determination of key analytes while others have reported incorporation into a neoprene wetsuit. In these conformations, the substrates which the sensors are printed upon need to be ultraflexible and capable of withstanding extensive individual mechanical stress. Therefore the composition, thickness and its combination of screen‐printed ink require extensive consideration. A common short‐coming within the field of screen‐printed derived sensors is the lack of consideration towards the substrate material employed, and is rather in favour of the development of new electrode geometries and screen‐printing inks. In this paper we explore the screen‐printing of graphite based electroanalytical sensing platforms onto graphic paper commonly used in house‐hold printers, and for the first time both tracing paper and ultraflexible polyester‐based substrates are used. These sensors are electrochemically benchmarked with the redox probes hexaammine‐ruthenium(III) chloride and potassium ferrocyanide(II). The effect of mechanical contortion upon two types of electrode substrates is also performed where it was found that these ultraflexible based polyester‐based electrodes are superior to the previously reported ultraflexible paper electrodes since they can withstand extensive mechanical contortion, yet they still give rise to useful electrochemical performances. Most importantly the ultraflexible polyester electrodes do not suffer from capillary action as observed in the case of paper‐based sensors causing the solution to wick‐up the electrode towards the electrical connections resulting in electrical shorting, therefore compromising the electrochemical measurement; as such this new substrate can be used as a replacement for paper‐based substrates and yet still be resilient to extreme mechanical contortion. A new configuration is also explored using these electrode substrate supports where the working carbon electrode contains the electrocatalyst, cobalt(II) phthalocyanine (CoPC), and is benchmarked towards the electroanalytical sensing of the model analytes citric acid and hydrazine which demonstrate excellent sensing capabilities in comparison to previously reported screen‐printed electrodes.

The Mediatorless Electroanalytical Sensing of Sulfide Utilizing Unmodified Graphitic Electrode Materials

“…This places the electrodes in the following order of reactivity: SPE > EPPGE > GCE > BDDE > BPPGE. It is noted that the value for the SPEs are consistent with those in previous literature [44][45][46]. As the peak-to-peak separations for these carbon based electrodes are similar when utilizing hexammineruthenium(III) chloride, ( Table 2) further benchmarking was undertaken using the Fe 2+ /Fe 3+ redox couple, since this is an inner-sphere probe that is known to be extremely sensitive to surface orientated functional groups, especially carbonyl groups.…”

“…A previously used carbon-graphite ink formulation (Product Code: C2000802P2; Gwent Electronic Materials Ltd., Gwent, UK) was first screen-printed onto a polyester flexible film (Autostat, 250 micron thickness) [44,48]. This layer was cured in a fan box oven (with a fan and extraction) at 60˝for 30 min.…”

Boron-doped diamond electrodes explored for the electroanalytical detection of 7-methylguanine and applied for its sensing within urine samples

“…C2000802P2; Gwent Electronic Materials Ltd, UK) was first screen-printed onto a polyester flexible film (Autostat, 250 µm thickness) [38]. This layer was cured in a fan oven at 60 degrees Celsius for 30 min.…”

l -Cysteine determination in embryo cell culture media using Co (II)-phthalocyanine modified disposable screen-printed electrodes

“…The same printing procedure described above was also applied to manufacture the CoPc-SPE. Both CoPc-SPE and SPE platforms has been extensively physico-chemical characterized in previous works by Foster et al [42,44].…”

“…As an alternative, the use of bulk-CoPc screen-printed electrodes (CoPc-SPEs) allows the mass production of reproducible electrodes since the CoPc is incorporated into the ink used to fabricate them. CoPc-SPE disposable platforms have been proved to exhibit excellent electrocatalytic properties towards the electrooxidation of compounds such as ascorbic acid, citric acid and hydrazine with high reproducibility in the electrochemical measurements compared with drop-casted SPEs [42][43][44]. The use of SPEs has also the big advantage of being economic, providing more reproducibility and repeatability, requiring neither previous polishing nor electrochemical conditioning.…”