Flexible and Stretchable Microneedle Patches with Integrated Rigid Stainless Steel Microneedles for Transdermal Biointerfacing.

Mina Rajabi,Reza Zandi Shafagh,Tommy Haraldson,Andreas Christin Fischer,Frank Niklaus,Wouter Van Der Wijngaart,Niclas Roxhed,Göran Stemme,Xian Jun Loh

doi:10.1371/journal.pone.0166330

Mina Rajabi, Reza Zandi Shafagh + Show 7 more

Open Access

https://doi.org/10.1371/journal.pone.0166330

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Abstract

This paper demonstrates flexible and stretchable microneedle patches that combine soft and flexible base substrates with hard and sharp stainless steel microneedles. An elastomeric polymer base enables conformal contact between the microneedle patch and the complex topography and texture of the underlying skin, while robust and sharp stainless steel microneedles reliably pierce the outer layers of the skin. The flexible microneedle patches have been realized by magnetically assembling short stainless steel microneedles into a flexible polymer supporting base. In our experimental investigation, the microneedle patches were applied to human skin and an excellent adaptation of the patch to the wrinkles and deformations of the skin was verified, while at the same time the microneedles reliably penetrate the surface of the skin. The unobtrusive flexible and stretchable microneedle patches have great potential for transdermal biointerfacing in a variety of emerging applications such as transdermal drug delivery, bioelectric treatments and wearable bio-electronics for health and fitness monitoring.

Highlights

Recent advances in flexible and stretchable electronics show great potential for wearable bioelectronics and epidermal sensor systems that are in contact with the surface of the human skin, e.g. for measuring physiological signals in diagnostics, and health and fitness monitoring applications [1,2]
We have demonstrated the feasibility of a flexible microneedle patch composed of a soft and flexible base substrate in combination with stiff and sharp stainless steel microneedles
The elastomeric polymer base enables conformal contact between the microneedle patch and the complex topography of the underlying skin, and the sharp microneedles reliably pierce into the skin

Summary

Introduction

Recent advances in flexible and stretchable electronics show great potential for wearable bioelectronics and epidermal sensor systems that are in contact with the surface of the human skin, e.g. for measuring physiological signals in diagnostics, and health and fitness monitoring applications [1,2]. Flexible and stretchable epidermal patches have been developed and demonstrated to monitor physiological parameters such as electrophysiological signals, skin temperature, skin hydration and sweat and movement disorders [1,2,3,4,5,6,7,8,9,10,11,12,13]. In contrast to epidermal patches, microneedles pierce and penetrate into the upper layers of the skin. Microneedles typically are 100–1000 μm long, which is sufficiently short to avoid touching nerve endings in the lower layers of the skin, thereby enabling minimally invasive and painless

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