Three distinct hydrogen sensing responses of palladium line patterns generated by femtosecond laser direct writing

Abstract

Application of a palladium nanostructure in hydrogen detection is a focus of current research due to its high sensitivity. In this paper, palladium nanometre films are fabricated using femtosecond laser decomposition of palladium acetate films. Their hydrogen sensing characteristics are studied as a function of hydrogen concentration and morphologies of palladium films. As palladium film morphologies vary from continuous to partially continuous and then to discontinuous, the corresponding hydrogen response changes from normal to pulse-like and then to switch-like. Their response characteristics are determined by the different combined effects of the formation of high-resistance palladium hydrogen and the corresponding narrowing of nanogaps between palladium nanoparticles.

Femtosecond‐Laser Direct Writing of Metallic Micro/Nanostructures: From Fabrication Strategies to Future Applications

“…The resulting helical microrobots were capable of performing steerable corkscrew motions at high speed in 3D, exhibiting great potential for the micromanipulation of biological cells or in vivo drug delivery. In addition, Qu and co‐workers reported the fabrication of hydrogen (H 2 ) sensors based on palladium patterns fabricated by the femtosecond‐laser direct two‐photon reduction of palladium acetate …”

“…In addition to silver micro/nanostructures, femtosecondlaser TPA photoreduction strategies have also been applied to other metals. [20,61,68,69] Duan and co-workers proposed a facile ionic liquid-assisted femtosecond-laser TPA photoreduction approach to fabricate subwavelength gold nanostructures in a AuCl 4 − ion aqueous solution. [61,68] With the use of a suitable ionic liquid and optimized laser fabrication parameters, the resolution of the gold nanostructure could reach as low as 228 nm, far beyond the optical diffraction limit.…”

“…In addition to the abovementioned applications, the fabrication of metal structures via FsLDW has also demonstrated potential in various scientific fields, such as micromechanics (Figure 1i), [85,86,[93][94][95][96] and microsensors. [69] For instance, by applying electroless copper plating on a prefabricated polymer template, Maruo and co-workers fabricated 3D metallic movable microparts, such as a microrotor and a microscrew, which could potentially be used in MEMS or LoC systems. [86] Duan and coworkers prepared 3D micromachines by combining FsLDW and the electroless plating of nickel-phosphorus.…”

“…In addition, Qu and co-workers reported the fabrication of hydrogen (H 2 ) sensors based on palladium patterns fabricated by the femtosecond-laser direct twophoton reduction of palladium acetate. [69]…”

Study of hydrogen detection response time with Pt-gated diodes fabricated on AlGaN/GaN heterostructure

“…Typically, the response time is defined as the interval of time from initial current increase to when the measured signal reaches 90% (t 90 ) of the total change, but response time definitions ending at percentages between 50% (t 50 ) and 70% of the total change have also been employed. [11][12][13][14][15][16][17] Table I summarizes previously reported response times for semiconductor-based hydrogen sensors.…”