An oxidized liquid metal-based microfluidic platform for tunable electronic device applications

Abstract

Easy movement of oxidized Galinstan in microfluidic channels is a promising way for the wide application of the non-toxic liquid metal. In this paper, two different surface modification techniques (physical and chemical) are reported, which dramatically improve the non-wetting characteristics of oxidized Galinstan in the microfluidic channel. In the physical technique, normal paper textures are transferred to the inner wall of polydimethylsiloxane (PDMS) channels and four types of nanoparticles are then coated on the surface of the wall for further improvement of the non-wetting characteristics. Highest advancing angle of 167° and receding angle of 151° are achieved on the paper-textured PDMS with titanium oxide (TiO2) nanoparticles. In the chemical technique, three types of inorganic acids are employed to generate dual-scale structures on the PDMS surface. The inner wall surface treated with sulfuric acid (H2SO4) shows the highest contact angle of 167° and a low hysteresis of ~14° in the dynamic measurement. Creating, transporting, separating and merging of oxidized Galinstan droplets are successfully demonstrated in the fabricated PDMS microfluidic channels. After optimization of these modification techniques, the potential application of tunable capacitors and electronic filters is realized by using liquid metal-based microfluidic devices.

Selectively plated stretchable liquid metal wires for transparent electronics

“…As can be seen from Fig. 3(a3) and (b3), some cracks are generated on the liquid-metal surface, which are attributed to the oxidation layer of the liquid metal [40]. These cracks have no influence on the electrical characteristics of the stretchable circuit.…”

“…S5(c2) and (c3) of the Supplementary data, reduced Galinstan requires more than 30 s to wet the adhesion layer, which has a width of 5 m. The increased rolling time still affects the edges of the adhesion layers, and this causes the edges of the liquid metal to become worse. Various adhesion materials or surface modification techniques could be used to overcome this issue [40]. Even though a smaller feature width (5 m) for the conductive pattern could not be achieved with a high accuracy using the proposed SLMP, the resolution of 10 m is enough to satisfy the requirements of SCB applications.…”

“…In our previous studies, the wetting behaviors of oxidized or HCl-treated Galinstan droplets on PDMS substrates are described [38,40]. Reduced Galinstan exhibits superlyophobicity on a PDMS substrate, as shown in Fig.…”

Mechanically Defined Microgels by Droplet Microfluidics

“…Microfluidic technology encompasses a variety of device systems made from silicon, glass, polymers, and metals . However, in academia the most established of all methods of microfluidic prototyping relies on using poly(dimethylsiloxane) (PDMS)‐based soft lithography nowadays.…”

Passive and active electromagnetic stabilization of free-surface liquid metal flows

“…One technology is 3D metal printing [13]. The other makes use of Galinstan to realize flexible electronics, tunable metamaterials and microfluidic devices [13,14,15]. Both would benefit highly from flow control.…”