# Main challenges of continuous monitoring of biomarkers through hydrogel micro-needles array

L Gautier, A Hoang, I Sorrentino, Y Thomas, I Texier

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To cite this version:

L Gautier, A Hoang, I Sorrentino, Y Thomas, I Texier. Main challenges of continuous monitoring of biomarkers through hydrogel micro-needles array. World Biomaterial Congress (WBC), May 2024, Daegu, South Korea. **hal-04904818**

HAL Id: hal-04904818

https://hal.science/hal-04904818v1

Submitted on 21 Jan 2025

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# Main challenges of continuous monitoring of biomarkers through hydrogel micro-needles array

L. Gautier¹, A. Hoang¹, I. Sorrentino¹, Y. Thomas¹, I. Texier¹

¹Université Grenoble Alpes, CEA, LETI-DTBS, Grenoble, France

*laurabelle.gautier@cea.fr

BACKGROUND&PURPOSE. The use of microneedles are more and more presented as potential future replacement of the traditional blood test. The main goal is to offer a mini invasive solution, which is easy to use and painless to patient. The micro-needle arrays are often less than 1mm in height to allow the stratum corneum perforation, the MN tip should reach the dermis. The interest to access the dermis is also to access the interstitial fluid, which is a good blood representative in terms of biomarkers. Currently the main successful studies used metallic or silicon micro-needles coupled with functionalized electrodes to perform some biomarkers detection (ions, pH, glucose, hormones, antibody...).

METHODS. Functionalized Dextran polysaccharide with different degree of substitution was used to manufacture the micro-needle array (MNA) by the well known micro-molding process. After observation of their general aspect, the MNA were evaluated by several means. Some artificial skin perforation tests, some compressive tests and some swelling studies were performed. Functionalized electrodes were then embedded in the hydrogel during MNA micromolding process, and conductivity, sodium detection and pH measurements were carried out.

RESULTS. After a few adjustments to the hydrogel formulation to improve the general appearance of the MNAs, the devices demonstrated very good perforation capabilities and good mechanical properties. On the other hand, MNAs tend to break during swelling, a problem that seems particularly linked to the geometry of the device. Conductivity tests have shown that the hydrogel becomes more and more conductive as it swells, even if it remains quite resistive. The measurements of sodium and pH in solution did not allow us to make satisfactory measurements, so leave room for interface improvement.

CONCLUSIONS. The strategy of using MN in cross-linked hydrogel is promising but difficult to achieve. Depending on the chemistry used and the geometry, MNAs are more or less easy to manufacture once the manufacturing process has been developed, the patches are hard and perforating. On the other hand, the chain network of dextran seems mechanically constrained, which leads to deformations and failures during the swelling of liquid. In addition, it is difficult to control the quality of the interface between the hydrogel and the measurement electrodes, which will require new experiments in the future.