Injection moulded microneedle sensor for real-time wireless pH monitoring

Abstract

This paper describes the development of an array of individually addressable pH sensitive microneedles using injection moulding and their integration within a portable device for real-time wireless recording of pH distributions in biological samples. The fabricated microneedles are subjected to gold patterning followed by electrodeposition of iridium oxide to sensitize them to 0.07 units of pH change. Miniaturised electronics suitable for the sensors readout, analog-to-digital conversion and wireless transmission of the potentiometric data are embodied within the device, enabling it to measure real-time pH of soft biological samples such as muscles. In this paper, real-time recording of the cardiac pH distribution, during ischemia followed by reperfusion cycles in cardiac muscles of male Wistar rats has been demonstrated by using the microneedle array.

Resource Efficient Pre-processor for Drift Removal in Neurochemical Signals

“…The drift can also be further divided into linear and non-linear drift where linear refers to a constant slope value of the drift in the input while non-linear indicates slope value of the drift changes over time. Within IrOx sensors, the OCP drifts are generally unidirectional as shown earlier on bench and also in an in vitro setup [4], [8], [9].…”

Microneedles: materials, fabrication, and biomedical applications

“…Similarly, micro-injection molding and hot embossing are used for the pattern transfer to obtain the microneedles in the desired material. For the micro-injection, the solution was injected into the cavities of the mold with a micro-injector by a compression process (Sammoura et al 2007;O'Mahony et al 2019;Mirza et al (2017)). The injection speed, melt temperature and secondary clamping pressure have a significant effect on the quality of microneedles during the injection process (Zhuang et al 2018).…”

Piezoelectric inkjet coating of injection moulded, reservoir-tipped microneedle arrays for transdermal delivery

“…3M Corporation have demonstrated transdermal drug delivery using both solid [22][23][24] and hollow [25] injection moulded microneedles, fabricated from medical-grade, liquid crystalline polymer materials under their microstructured transdermal system (MTS) brand. Others have used injection moulding techniques to create microneedles in materials such as polycarbonate, polyethylene terephthalate (PET), cyclic olefin copolymer (COC), and polyoxymethylene [26][27][28][29].…”