Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing

Abstract

In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.

Electrodeposited Iron as a Biocompatible Material for Microneedle Fabrication

“…Fluid extractsw ere taken from electroplatedi ron coupons incubated in cell growth mediumf or 24 hoursa t3 7 8C. Undiluted electroplated iron extracts were tested alongw ith diluted iron extracts againsth uman epidermal keratinocytesu sing the MTT assay (Figure 8), which has been used previously to validate the cytotoxicityofs everalm icroneedle materials [31].T his assay is ac ell based assaytod etermine viability by exposing ac ell line to the material being tested and to ad ye,w hich an intracellular enzyme metabolizes into an insoluble productt hat is then quantified [32].T he rate are which the enzyme can metabolize the dye is ar eflection of the test material'se ffecto nt he cells.I ron extracts were tested at 10 %, 25 %, 50 %, and 100 %p urity and were compared to tissue culture wells and silver ions as the negative and positive controls,r espectively.P ure extracts exhibited 71 %v iability,w ith diluted iron extracts approaching nearly 100 %v iability for the remainder of the tested extracts.…”

Wearable Bio and Chemical Sensors

“…Good correlations were found between interstitial fluid and reference plasma glucose levels. Other analytes measured using microneedle sampling were hydrogen peroxide and ascorbic acid in which sampling was integrated with sensing via chemically modified carbon fiber bundles [27], and lactate, using carbon paste microneedle arrays. In the latter case, the need for integrated microchannels was avoided and extraction of the interstitial fluid was avoided, as the microneedles themselves were provided with inherent sensing capabilities [28].…”

Editors' Choice—Review—In Vivo and In Vitro Microneedle Based Enzymatic and Non-Enzymatic Continuous Glucose Monitoring Biosensors

“…51 The microneedle arrays were fabricated using dynamic light micro-stereolithography system and the microarray design was made using commercially available computer-aided design software 52 . Openings in the top insulation layer of the flexible flat cable were created by a CO 2 laser ablation exposing the underlying conductors.…”