Laser‐Induced Colloidal Writing of Organometallic Precursor–Based Repeatable and Fast Pd–Ni Hydrogen Sensor

Abstract

The advent of hydrogen economy brings new challenges in terms of safety and sensing with a need for fast and low‐cost monitoring of hydrogen concentration. Herein, a repeatable process for the fabrication of Pd‐based hydrogen sensor is presented. First, a room‐temperature reaction of organometallic precursors yields colloidal Pd/Ni alloyed nanoparticles. This organic solvent‐based colloidal dispersion shows stability over months even with a relatively high metal content (≈1 wt%). Then, a laser induced microbubble deposits the nanoparticles in predetermined patterns from a microdroplet dispersion that is placed on a glass slide. An optical microscope monitors the writing process while a multimeter measures the sensor's conductance, assessing the success of the fabrication process. The fabricated sensors demonstrate excellent hydrogen detection performance in terms of response time, signal stability, and detection limit down to 100 ppm of H2 in air at room temperature.

Laser‐Based Printing: From Liquids to Microstructures

“…In many cases, excluding Roy et al [77] and Edri et al [70] (Figure 4h), a non-continuous deposition is formed. However, it was shown [69,79,84] that modulations of the laser enable the formation of continuous patterns (Figure 4i). This is achieved by gaining better control over the size of the microbubble and preventing it from being pinned to the deposited material while moving.…”

“…[76] Products: Microbubble assisted printing was used for depositing various material families. Specific examples include Ag NPs, [69] Cu NPs, [69] Pd/Ni NPs, [84] quantum dots (QDs), [68,[71][72][73] polystyrene, [72,74] polyaniline (PANI), [70] soft oxometalate nanotubes (SOMs), [77] glycine, [77] paracetamol, [77] CNTs, [77] and Si-Au core-shell NPs. [79] The minimal deposited feature size is affected mainly by the size of the microbubble, as the deposition occurs at its contact area with the substrate.…”

“…The attained feature sizes ranged from ≈510 nm [71] up to 50 µm. [68][69][70][71][72][73]77,84] Using this method, hydrogen sensors were formed, [84,86] as well as barcodes [68] (Figure 4j) and improved SERS fiber probes. [79] While to the best of our knowledge arbitrary 3D printing was not demonstrated, 3D hollow spherical structures can be fabricated by allowing particles to cover the formed microbubble (Figure 4k).…”

“…Wavelength [nm] 405, [75] 532, [68][69][70][71][72]74] 1064 [73,77,79] Laser power [mW] 0.28-250 [68][69][70][71][72][73][74]77] Objective lens 5×, [74] 40×, [69,70,79] 60×, [72] 100× [68,[71][72][73]77] Printing velocity 10 µm s −1 -10 mm s −1 [68][69][70][71][72]74,77,84] Substrate Glass, [67][68][69]76,83] PET, [67] substrates coated with Au, [68,[71][72][73] Ag, [74] or a monolayer of MoS 2 [72] Continuous phase Water, [68,69,…”

Highly Sensitive and Flexible Pressure Sensor Prepared by Simple Printing Used for Micro Motion Detection

“…Smart wearable flexible sensors with high sensitivity and antifatigue performance have attracted much attention due to their potential applications in healthcare, artificial intelligence, and medical motions . Sensors can transmit multiple types of signals like optical signals and biological signals . The mechanical motion is the most common and indispensable part in nature, among them, pressure can be converted into electrical signals and outputs them through pressure sensors.…”