To achieve an effective surface-enhanced Raman scattering (SERS) sensor with periodically distributed “hot spots” on wafer-scale substrates, we propose a hybrid approach combining physical nano-imprint lithography and a chemical deposition method to form a silver microbead array. Nano-imprint lithography (NIL) can lead to mass-production and high throughput, but is not appropriate for generating strong “hot-spots.” However, when we apply electrochemical deposition to an NIL substrate and the reaction time was increased to 45 s, periodical “hot-spots” between the microbeads were generated on the substrates. It contributed to increasing the enhancement factor (EF) and lowering the detection limit of the substrates to 4.40 × 10⁶ and 1.0 × 10⁻¹¹ M, respectively. In addition, this synthetic method exhibited good substrate-to-substrate reproducibility (RSD < 9.4%). Our research suggests a new opportunity for expanding the SERS application.

We have demonstrated a direct laser writing (DLW) process that uses a femtosecond laser to fabricate a nano-micro hierarchical structure for a large capacitance microsupercapacitor (MSC) electrode. By applying a two-photon polymerization-based DLW technique, a photoresist (PR) nano-pillar pattern was fabricated on a pre-defined PR interdigitated electrode (PR-IDE) pattern to form a nano-micro hierarchical structure. Carbon pyrolysis converted a PR-IDE with a nano-micro hierarchical structure to a PR derived carbon (PRC)-IDE while maintaining the aspect ratio of the pillar structure. The electrochemical performance of the PRC-MSC is improved by introducing the nano-pillar pattern to the PRC-IDE, resulting in larger areal capacitance of the as-fabricated PRC-IDE compared to the PRC-IDE with a micropattern only. The PRC-IDE with a nano-micro hierarchical structure in this study could be further applied as a backbone electrode structure for a high power pseudo-capacitor.

Air, a widely recognized dielectric material, is employed as a dielectric layer in this study. We present a triboelectric sensor with a laser-induced graphene (LIG) electrode and an air-trapped pad using silicone rubber (SR). A very thin device with a thickness of 1 mm and an effective gap for contact–separation between the films of silicone rubber and polyimide (PI) of 0.6 mm makes the device extremely highly sensitive for very low amplitudes of pressure. The fabrication of LIG as an electrode material on the surface of PI is the key reason for the fabrication of the thin sensor. In this study, we showed that the fabricated air-trapped padded sensor (ATPS) has the capability to generate an output voltage of ~32 V, a short-circuit current of 1.2 µA, and attain a maximum power density of 139.8 mW m⁻². The performance of the ATPS was compared with a replicated device having a hole on the pad, allowing air to pass through during contact–separation. The observed degradation in the electrical output suggests that the trapped air in the pad plays a crucial role in enhancing the output voltage. Therefore, the ATPS emerges as an ultra-sensitive sensor for healthcare sensing applications.