Biomolecule-Interactive Flexible Light Emitting Capacitor Display.

Ultrathin, lightweight, flexible, and conformable interactive displays that transduce external stimuli into human-readable signals are essential for emerging applications, such as wearable electronics, human-machine interfaces, and soft robots. Herein, a biomolecule-interactive flexible light emitting capacitor (LEC) display (BIO-LEC) capable of dynamic and quantitative visualization of biomolecules through naked-eye detectable electroluminescence (EL) emission is reported. BIO-LEC comprises a coplanar LEC light source at the bottom, and a designed microfluidic chip as sampling compartment at the top. The quantitative measurement feature of BIO-LEC is achieved by introducing the top liquid electrode, which possesses a unique long dielectric realization time, in the microfluidic chip. BIO-LEC is novel for the following reasons, 1) simple stimuli response principle based on correlating EL intensity to dielectric properties of the top liquid electrode; 2) simple test conditions whereby no labeling is required in the analyte solution to optically detect biomolecules; 3) effective sampling method through the design of an integrated microfluidic chip for hosting the top liquid electrode, ensuring good reproducibility and preventing contamination; 4) sensitive detection limit for heparin concentrations at clinically relevant levels, and 5) high compliance with industrial manufacturing standards.

Life cycle assessment of single-use surgical and embedded filtration layer (EFL) reusable face mask.

BACKGROUND: The outbreak of the COVID-19 pandemic has led to an unprecedented amount of face mask consumption around the world. The increase in face mask consumption has brought focus to their environmental impact. To keep up with the increased demand for face masks, different variations of reusable face masks such as the embedded filtration layer (EFL) reusable face mask have emerged in the market. This study quantifies the environmental impact of the EFL reusable face mask and the single-use surgical face mask. METHODS: The life cycle assessment (LCA) study of the entire value chain from cradle-to-grave is applied to each face mask. Both face masks are evaluated over 1 functional unit (FU) of 31 12-h days for a single person. The ReCiPe method with the Hierachist perspective was applied. A total of nine impact categories as well as the generated waste of each face mask are evaluated. RESULTS: The results show that for 1 functional unit, the use of single-use surgical face mask and EFL reusable face mask will contribute 0.580 kg CO2-eq and 0.338 kg CO2-eq to climate change and generate 0.004 kg and 0.0004 kg of waste respectively. CONCLUSION: Comparing both face masks, the EFL reusable face mask will have a lower emission of at least 30% in terms of the generated waste and the impact categories considered, except for water depletion, freshwater eutrophication, marine eutrophication, and human toxicity.

Patterned surface with controllable wettability for inkjet printing of flexible printed electronics.

Appropriate control of substrate surface properties prior to inkjet printing could be employed to improve the printing quality of fine resolution structures. In this paper, novel methods to fabricate patterned surfaces with a combination of hydrophilic and hydrophobic properties are investigated. The results of inkjet printing of PEDOT/PSS conductive ink on these modified surfaces are presented. Selective wetting was achieved via a two-step hydrophilic-hydrophobic coating of 3-aminopropyl trimethoxysilane (APTMS) and 3M electronic grade chemical respectively on PET surfaces; this was followed by a selective hydrophilic treatment (either atmospheric O2/Ar plasma or UV/ozone surface treatment) with the aid of a Nickel stencil. Hydrophobic regions with water contact angle (WCA) of 105° and superhydrophilic regions with WCA <5° can be achieved on a single surface. During inkjet printing of the treated surfaces, PEDOT/PSS ink spread spontaneously along the hydrophilic areas while avoiding the hydrophobic regions. Fine features smaller than the inkjet droplet size (approximately 55 µm in diameter) can be successfully printed on the patterned surface with high wettability contrast.

Inkjet printing of multi-walled carbon nanotube/polymer composite thin film for interconnection.

In this paper, multi-walled carbon nanotube (MWCNT) ink was selectively patterned by inkjet printing on substrates to form conductive traces and electrodes for interconnection application. MWCNT was firstly functionalized using concentrated acid and dispersed in deionized water to form a colloidal solution. Various concentrations of MWCNT were formulated to test the stability of the solution. The printability of the MWCNT ink was examined against printing temperature, ink concentration and ink droplet pitch. Rheological properties of the ink were determined by rheometer and sessile drop method. The electrical conductivity of the MWCNT pattern was measured against multiple printing of MWCNT on the same pattern (up to 10 layers). While single layer printing pattern exhibited highest resistance, the CNT entangled together and formed a random network with more printed layers has higher conductivity. The electrical properties of the printed film was compared to a composite ink of CNT and conducting polymer (CNT ink was mixed with conductive polymer solution, Poly(3,4-ethylenedioxythiophene)-Poly(styrenesulfonate) (PEDOT:PSS)). Scanning electron microscopy (SEM) was used to observe the surface structure and atomic force microscopy (AFM) was used to study the morphology of the printed film under different conditions.