Experimental Characterization of Inkjet-Printed Stretchable Circuits for Wearable Sensor Applications.

Jumana Abu-Khalaf,Ala’Aldeen Al-Halhouli,Saleh Eisa,Razan Saraireh

doi:10.3390/s18103476

Abstract

This paper introduces a cost-effective method for the fabrication of stretchable circuits on polydimethylsiloxane (PDMS) using inkjet printing of silver nanoparticle ink. The fabrication method, presented here, allows for the development of fully stretchable and wearable sensors. Inkjet-printed sinusoidal and horseshoe patterns are experimentally characterized in terms of the effect of their geometry on stretchability, while maintaining adequate electrical conductivity. The optimal fabricated circuit, with a horseshoe pattern at an angle of 45°, is capable of undergoing an axial stretch up to a strain of 25% with a resistance under 800 Ω. The conductivity of the circuit is fully reversible once it is returned to its pre-stretching state. The circuit could also undergo up to 3000 stretching cycles without exhibiting a significant change in its conductivity. In addition, the successful development of a novel inkjet-printed fully stretchable and wearable version of the conventional pulse oximeter is demonstrated. Finally, the resulting sensor is evaluated in comparison to its commercially available counterpart.

Highlights

Printed electronics (PE) is a technology which involves techniques developed to print electrical and electronic devices on various types of substrates
The work presented in this paper investigates the use of inkjet printing of conductive silver nanoparticle (NP) based ink on PDMS substrates for the development of stretchable circuits, which are comparable to their photolithography-fabricated counterparts
It is evident that conventional electronics are rigid, bulky, and not directly suitable for wearing. To enhance their wearability, rigid electronic circuits are either transformed into flexible and stretchable circuits or are embedded in a stretchable platform [22,31]. We have identified this as our primary objective as it can potentially create the first fully functional inkjet-printed stretchable circuit containing embedded optoelectronic components

Summary

Introduction

Printed electronics (PE) is a technology which involves techniques developed to print electrical and electronic devices on various types of substrates. The manufacturing of conventional printed circuits employs a mix-subtractive method, while a fully additive method is employed in PE [2]. The latter method is based on the deposition of materials on the surface of a substrate and is divided into two major printing categories; contact and non-contact printing [3]. This classification is based on the presence of physical contact between the printer and the substrate. Non-contact printing techniques include screen-printing, slot-die coating, and inkjet printing [4,5,6]

Methods

Discussion

Conclusion