The application of Laser Induced Graphene (LIG) to a multitude of sensing applications is outlined. A discussion of the material origins and the intrinsic properties that make it optimal for sensing is followed by analyses of exemplar motion, chemical and biological sensors from the literature. The rapid growth of research output on LIG sensors is warranted due to the remarkable capabilities of such a cost effective and easily manufactured substrate. Subject to standardization of manufacturing, LIG may achieve commercial viability where prior graphene based materials have fallen short.

Conductive microneedle patches based on carbon nanoparticle composites in which cellulose acetate phthalate (CAP) or polystyrene (PS) acted as a binder were investigated. The electrochemical properties of the composite system were assessed using ferrocyanide as a redox probe and compared with screen printed carbon electrodes. Preliminary investigations of biodegradability were conducted with the influence of soil interment assessed by electron microscopy. While the PS microneedles exhibited no breakdown, the CAP systems were found to be substantially degraded after one week with complete removal of the needle tips and, hence, piercing capability.

The combination of paraffin wax and O,O′-bis(2-aminopropyl) polypropylene glycol–block–polyethylene glycol–block–polypropylene glycol was used as a phase-change material (PCM) for the controlled delivery of curcumin. The PCM was combined with a graphene-based heater derived from the laser scribing of polyimide film. This assembly provides a new approach to a smart patch through which release can be electronically controlled, allowing repetitive dosing. Rather than relying on passive diffusion, delivery is induced and terminated through the controlled heating of the PCM with transfer only occurring when the PCM transitions from solid to liquid. The material properties of the device and release characteristics of the strategy under repetitive dosing are critically assessed. The delivery yield of curcumin was found to be 3.5 µg (4.5 µg/cm2) per 3 min thermal cycle.

The laser-induced modification of polyimide substrates to yield conductive graphitised tracks sensitive to the solution pH is investigated. The influence of laser output and operating characteristics on the surface morphology and the consequential impact on electrochemical properties have been evaluated. Several sensor formats have been pursued using both potentiometric and voltammetric methodologies and found to provide a stable means of determining pH. While the potentiometric system was found to provide sub-Nernstian responses, the voltammetric system employing a riboflavin (vitamin B2) redox probe was found to exhibit classic Nernstian profiles (56 mV/pH). The versatility of the laser patterning on polyimide is shown to yield a mechanically flexible double-sided probe that could be suitable for use in a wide variety of clinical applications.

A series of naphthoquinone-aminophenol derivatives have been synthesized on the basis that their conjugation with a suitable drug candidate could provide a means through which the latter could be released upon the imposition of an appropriate oxidation potential. The approach is based on a three component assembly in which the naphthoquinone redox centre serves as a reporter unit allowing electrochemical interrogation without release of the drug. The central aminophenol serves as the tether to which the drug is linked via an ether bond. Upon oxidation of the aminophenol - ether component, transition of the latter to quinone imine results in the release of the drug. The electrochemical properties of the model system are investigated and the impact of the release process on the functional groups intrinsic to the drug component is critically considered.

Catheter related blood stream infection is an ever present hazard for those patients requiring venous access and particularly for those requiring long term medication. The implementation of more rigorous care bundles and greater adherence to aseptic techniques have yielded substantial reductions in infection rates but the latter is still far from acceptable and continues to place a heavy burden on patients and healthcare providers. While advances in engineering design and the arrival of functional materials hold considerable promise for the development of a new generation of catheters, many challenges remain. The aim of this review is to identify the issues that presently impact catheter performance and provide a critical evaluation of the design considerations that are emerging in the pursuit of these new catheter systems.