Because of high sensitivity, mechanical robustness, lightweight and wearability, flexible capacitive pressure transducer has been widely considered one of the most critical soft electronics in ...wearable consumables and e-skins. The enhancement of the pressure sensitivity of a flexible capacitive sensor relies on the introduction of interfacial microstructure to the dielectric layer. We demonstrate a new methodology to fabricate flexible capacitive sensors with copper-plated polyimide (PI) films as the electrodes and a porous polydimethylsiloxane (PDMS) layer 3D printed via the direct-ink-writing approach. Time-of-flight secondary ion mass spectrometry is developed to optimize the electroless copper plated PI films. What is further examined is the impact of the geometric complexity of the cellular PDMS structure, including filament width, spacing and alignment, on sensitivity, repeatability and reliability of the developed capacitive sensor. A robotic gripper equipped with our flexible pressure sensor showcases its competence to grip a soft target with well-posed force control. It is expected that our proposed sensor design and manufacturing methodology will advance the development of soft electronics and wearable sensors.
The facile technology of hyperthermal hydrogen‐induced cross‐linking (HHIC) has recently been employed to efficiently cross‐link the typical surface modification material of poly acrylic acid (PAA) ...on polymer substrates, such as polylactic acid substrates, parylene C substrates and hydrophobic polypropylene substrates. This paper systematically studied the HHIC induced self‐cross‐linking of PAA without polymer substrates. It was found that the H was cleaved not only from the CH, but also from the surface functional group COOH, evidenced by both X‐ray photoelectron spectroscopy (XPS) measurement and the water contact angle test. We explained the self‐cross‐linking process as a result of both CC bonding and COOC bonding. Meanwhile, it was also found that PAA on different substrates can also be cross‐linked by secondary electron generated by X‐ray radiation during XPS analysis, which could be the main reason for wide variations of different reported XPS results.
Hyperthermal hydrogen‐induced cross‐linking (HHIC), a relatively new technologywith several advantages such as low temperature treatment, both large area and local treatment, without requirement of crosslinking agent and without contamination, it can be seen that ‐H cleaves from ‐C‐H and ‐O‐H, and then both ‐COOC‐ and ‐C‐C‐ bonds form subsequently, finally leading to the cross‐linking of original PAA.
Abstract
All-solid-state lithium-sulfur batteries offer a compelling opportunity for next-generation energy storage, due to their high theoretical energy density, low cost, and improved safety. ...However, their widespread adoption is hindered by an inadequate understanding of their discharge products. Using X-ray absorption spectroscopy and time-of-flight secondary ion mass spectrometry, we reveal that the discharge product of all-solid-state lithium-sulfur batteries is not solely composed of Li
2
S, but rather consists of a mixture of Li
2
S and Li
2
S
2
. Employing this insight, we propose an integrated strategy that: (1) manipulates the lower cutoff potential to promote a Li
2
S
2
-dominant discharge product and (2) incorporates a trace amount of solid-state catalyst (LiI) into the S composite electrode. This approach leads to all-solid-state cells with a Li-In alloy negative electrode that deliver a reversible capacity of 979.6 mAh g
−1
for 1500 cycles at 2.0 A g
−1
at 25 °C. Our findings provide crucial insights into the discharge products of all-solid-state lithium-sulfur batteries and may offer a feasible approach to enhance their overall performance.
Aluminum (Al) placed in hot water (HW) at 90 °C is roughened due to its reaction with water, forming Al hydroxide and Al oxide, as well as releasing hydrogen gas. The roughened surface is thus ...hydrophilic and possesses a hugely increased surface area, which can be useful in applications requiring hydrophilicity and increased surface area, such as atmospheric moisture harvesting. On the other hand, when using HW to roughen specified areas of an Al substrate, ways to protect the other areas from HW attacks are necessary. We demonstrated that self-assembled monolayers (SAMs) of a fluorinated phosphonic acid (FPA, CF
(CF
)
(CH
)
P(=O)(OH)
) derivatized on the native oxide of an Al film protected the underneath metal substrate from HW attack. The intact wettability and surface morphology of FPA-derivatized Al subjected to HW treatment were examined using contact angle measurement, and scanning electron microscopy and atomic force microscopy, respectively. Moreover, the surface and interface chemistry of FPA-derivatized Al before and after HW treatment were investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS), verifying that the FPA SAMs were intact upon HW treatment. The ToF-SIMS results therefore explained, on the molecular level, why HW treatment did not affect the underneath Al at all. FPA derivatization is thus expected to be developed as a patterning method for the formation of hydrophilic and hydrophobic areas on Al when combined with HW treatment.
Display omitted
•Bioaccessibility of cobalt in stainless steels important from a legislative view.•Surface oxide and metal release of austenitic stainless steel 316L studied.•Metallic cobalt ...homogeneously co-located with nickel beneath the surface oxide.•Cobalt traces released with other metals upon surface reformation and passivation.•Surface enrichment of cobalt due to precipitation of released cobalt in PBS.
Since 2021, cobalt (Co) is in Europe classified as carcinogen in quantities exceeding 0.1 wt-%. This affects nickel-rich stainless steels, which contain about 0.2 wt-% Co impurities. Previous findings show the bioaccessibility of Co in stainless steel to be primarily determined by the corrosion resistance. It has been unclear whether Co is distributed heterogeneously in the alloy and the outermost surface and whether a specific location would pose a risk for Co release under specific exposure conditions. This study aimed at locating Co in stainless steel 316L (0.2 wt-% Co) surfaces prior to and after exposure to different synthetic body fluids for 24 h at 37 °C. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry (ICPMS) investigated the location of Co in the surface oxide and extent of release along with other metals (iron, chromium, nickel, and manganese) into synthetic biological fluids (gastric fluid, pH 1.5; lysosomal fluid, pH 4.5; phosphate buffered saline-PBS, pH 7.4). Co was homogeneously distributed along with metallic nickel beneath the surface oxide and co-released with other metals upon surface reformation and passivation. Exposure in PBS resulted in the incorporation of both Co and phosphate in the oxide.
Condensed octadecylphosphonic acid (OPA) dimers, i.e., two OPA molecules combined with the loss of a water molecule, were detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS) on OPA ...self-assembled monolayers (SAMs) that are only weakly bonded on the native oxide layer of a silicon wafer. In contrast, these condensed dimers were absent on OPA SAMs formed on the oxide layer of an aluminum film, where the OPA molecules are chemically bonded on the substrate through a P−O−Al linkage. These observations lead us to conclude that the OPA molecules in their SAMs have to be free from chemical bonding with the substrate in order for the primary ion beam to generate ion fragments of the condensed dimer. We demonstrate that the detection of condensed OPA dimers serves as an analytical criterion for TOF-SIMS to reveal the bonding mode of OPA molecules in their SAMs on different oxides.
Crystallization of a catalytically important molecular sieve SAPO-34 was examined under dry gel conversion conditions including steam-assisted conversion (SAC) and vapor-phase transport (VPT). The ...progressive changes in the structure of solid gel phases were monitored by powder XRD, SEM, and several solid-state NMR techniques involving 31P, 27Al, 29Si, and 13C. The results suggest that the formation pathways under VPT and SAC appear to be similar: SAPO-34 crystallizes from a semicrystalline precursor with a layered structure held mainly by weak nonbonding interactions. AFM data indicate that the crystal growth mechanism is “birth and spread” and that the fast nucleation on the (001) crystal face likely results from simultaneous transformation of many small domains of precursor to SAPO-34 via cooperative bond breaking and reforming. 29Si NMR results suggest that Si incorporation occurs slowly via amorphous aluminosilicate species. These findings provide new physical insights into the formation of SAPO-34.
PDF
