Abstract
Conventional microneedles (MNs) have been extensively reported and applied toward a variety of biosensing and drug delivery applications. Hydrogel forming MNs with the added ability to electrically track health conditions in real-time is an area yet to be explored. The first conductive hydrogel microneedle (HMN) electrode that is capable of on-needle pH detection with no postprocessing required is presented here. The HMN array is fabricated using a swellable dopamine (DA) conjugated hyaluronic acid (HA) hydrogel, and is embedded with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) to increase conductivity. The catechol-quinone chemistry intrinsic to DA is used to measure pH in interstitial fluid (ISF). The effect of PEDOT:PSS on the characteristics of the HMN array such as swelling capability and mechanical strength is fully studied. The HMN's capability for pH measurement is first demonstrated using porcine skin equilibrated with different pH solutions ranging from 3.5 to 9. Furthermore, the HMN-pH meter is capable of in vivo measurements with a 93% accuracy compared to a conventional pH probe meter. This HMN technology bridges the gap between traditional metallic electrochemical biosensors and the direct extraction of ISF, and introduces a platform for the development of polymeric wearable sensors capable of on-needle detection.
| Original language | English (US) |
|---|---|
| Article number | 2200201 |
| Journal | Small |
| Volume | 18 |
| Issue number | 45 |
| DOIs | |
| State | Published - Nov 10 2022 |
Funding
This research was supported by the Natural Sciences and Engineering Research Council of Canada, Discovery grant and Poudineh's University of Waterloo start\u2010up funding. The authors would like to acknowledge Dr. Kohandel's group for providing NIH\u20103T3 cells and thank Dr. Nafiseh Moghimi for her aid in the biocompatibility experiments. The authors additionally thank Kaiping Zhang for his help with the mechanical strength tests. The authors would also like to acknowledge the Giga\u2010to\u2010Nano Center for use of their cleanroom, Waterloo Advanced Technology Laboratory for use of their Au evaporator, and the University of Waterloo's animal facility and staff for help with the rat experiments. This research was supported by the Natural Sciences and Engineering Research Council of Canada, Discovery grant and Poudineh's University of Waterloo start-up funding. The authors would like to acknowledge Dr. Kohandel's group for providing NIH-3T3 cells and thank Dr. Nafiseh Moghimi for her aid in the biocompatibility experiments. The authors additionally thank Kaiping Zhang for his help with the mechanical strength tests. The authors would also like to acknowledge the Giga-to-Nano Center for use of their cleanroom, Waterloo Advanced Technology Laboratory for use of their Au evaporator, and the University of Waterloo's animal facility and staff for help with the rat experiments.
Keywords
- catechol-quinone chemistry
- conductive hydrogel microneedles
- interstitial fluid
- on-needle sensing
- pH-sensing
- real-time measurements
ASJC Scopus subject areas
- Biotechnology
- General Chemistry
- Biomaterials
- General Materials Science