Dipstick and lateral-flow formats have dominated rapid diagnostics over the last three decades. These formats gained popularity in the consumer markets due to their compactness, portability and facile interpretation without external instrumentation. However, lack of quantitation in measurements has challenged the demand of existing assay formats in consumer markets. Recently, paper-based microfluidics has emerged as a multiplexable point-of-care platform which might transcend the capabilities of existing assays in resource-limited settings. However, paper-based microfluidics can enable fluid handling and quantitative analysis for potential applications in healthcare, veterinary medicine, environmental monitoring and food safety. Currently, in its early development stages, paper-based microfluidics is considered a low-cost, lightweight, and disposable technology. The aim of this review is to discuss: (1) fabrication of paper-based microfluidic devices, (2) functionalisation of microfluidic components to increase the capabilities and the performance, (3) introduction of existing detection techniques to the paper platform and (4) exploration of extracting quantitative readouts via handheld devices and camera phones. Additionally, this review includes challenges to scaling up, commercialisation and regulatory issues. The factors which limit paper-based microfluidic devices to become real world products and future directions are also identified.

Materials with nonlinear optical (NLO) properties have significant applications in different fields, including nuclear science, biophysics, medicine, chemical dynamics, solid physics, materials science and surface interface applications. Quinoline and carbazole, owing to their electron-deficient and electron-rich character respectively, play a role in charge transfer applications in optoelectronics. Therefore, an attempt has been made herein to explore quinoline–carbazole based novel materials with highly nonlinear optical properties. Structural tailoring has been made at the donor and acceptor units of two recently synthesized quinoline–carbazole molecules (Q1, Q2) and acceptor–donor–π–acceptor (A–D–π–A) and donor–acceptor–donor–π–acceptor (D–A–D–π–A) type novel molecules Q1D1–Q1D3 and Q2D2–Q2D3 have been quantum chemically designed, respectively. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) computations are performed to process the impact of acceptor and donor units on photophysical, electronic and NLO properties of selected molecules. The λ_max values (321 and 319 nm) for Q1 and Q2 in DSMO were in good agreement with the experimental values (326 and 323 nm). The largest shift in absorption maximum is displayed by Q1D2 (436 nm). The designed compounds (Q1D3–Q2D3) express absorption spectra with an increased border and with a reduced band gap compared to the parent compounds (Q1 and Q2). Natural bond orbital (NBO) investigations showed that the extended hyper conjugation and strong intramolecular interaction play significant roles in stabilising these systems. All molecules expressed significant NLO responses. A large value of β_tot was elevated in Q1D2 (23 885.90 a.u.). This theoretical framework reveals the NLO response properties of novel quinoline–carbazole derivatives that can be significant for their use in advanced applications.

The rapidly expanding number of mobile medical applications have the potential to transform the patient–healthcare provider relationship by improving the turnaround time and reducing costs. In September 2013, the U.S. Food and Drug Administration (FDA) issued guidance to regulate these applications and protect consumers by minimising the risks associated with their unintended use. This guidance distinguishes between the subset of mobile medical apps which may be subject to regulation and those that are not. The marketing claims of the application determine the intent. Areas of concern include compliance with regular updates of the operating systems and of the mobile medical apps themselves. In this article, we explain the essence of this FDA guidance by providing examples and evaluating the impact on academia, industry and other key stakeholders, such as patients and clinicians. Our assessment indicates that awareness and incorporation of the guidelines into product development can hasten the commercialisation and market entry process. Furthermore, potential obstacles have been discussed and directions for future development suggested.

The global need for renewable sources of energy has compelled researchers to explore new sources and improve the efficiency of the existing technologies. Solar energy is considered to be one of the best options to resolve climate and energy crises because of its long-term stability and pollution free energy production. Herein, we have synthesized a small acceptor compound (TPDR) and have utilized for rational designing of non-fullerene chromophores (TPD1–TPD6) using end-capped manipulation in A2–A1–D–A1–A2 configuration. The quantum chemical study (DFT/TD-DFT) was used to characterize the effect of end group redistribution through frontier molecular orbital (FMO), optical absorption, reorganization energy, open circuit voltage (Voc), photovoltaic properties and intermolecular charge transfer for the designed compounds. FMO data exhibited that TPD5 had the least ΔE (1.71 eV) with highest maximum absorption (λ_max) among all compounds due to the four cyano groups as the end-capped acceptor moieties. The reorganization energies of TPD1–TPD6 hinted at credible electron transportation due to the lower values of λ_e than λ_h. Furthermore, open circuit voltage (Voc) values showed similar amplitude for all compounds including parent chromophore, except TPD4 and TPD5 compounds. These designed compounds with unique end group acceptors have the potential to be used as novel fabrication materials for energy devices.

A donor–π–acceptor type series of Triphenylamine–dicyanovinylene-based chromophores (DPMN1–DPMN11) was designed theoretically by the structural tailoring of π-linkers of experimentally synthesized moleculesDTThandDTTzto exploit changes in the optical properties and their nonlinear optical materials (NLO) behaviour. Density functional theory (DFT) computations were employed to understand the electronic structures, absorption spectra, charge transfer phenomena and the influence of these structural modifications on NLO properties. Interestingly, all investigated chromophores exhibited lower band gap (2.22–2.60 eV) with broad absorption spectra in the visible region, reflecting the remarkable NLO response. Furthermore, natural bond orbital (NBO) findings revealed a strong push–pull mechanism inDPMN1–DPMN11as donor and π-conjugates exhibited positive, while all acceptors showed negative values. Examination of electronic transitions from donor to acceptor moieties via π-conjugated linkers revealed greater linear (〈α〉 = 526.536–641.756 a.u.) and nonlinear (β_tot= 51 313.8–314 412.661 a.u.) response. It was noted that the chromophores containing imidazole in the second p-linker expressed greater hyperpolarizability when compared with the ones containing pyrrole. This study reveals that by controlling the type of π-spacers, interesting metal-free NLO materials can be designed, which can be valuable for the hi-tech NLO applications.

A series of derivatives (DOCD2–DOCD6) with D–π–A configuration was designed by substituting various efficient donor moieties via the structural tailoring of o-DOC6-2F. Quantum-chemical approaches were used to analyze the optoelectronic properties of the designed chromophores. Particularly, M06/6-311G(d,p) functional was employed to investigate the non-linear optical (NLO) response (linear polarizability ⟨α⟩, first (β_tot) and second ( $$\upgamma$$γ _tot) order hyperpolarizabilities) of the designed derivatives. A variety of analyses such as frontier molecular orbital (FMO), absorption spectra, transition density matrix (TDMs), density of states (DOS), natural bond orbital (NBO) and global reactivity parameters (GRPs) were employed to explore the optoelectronic response of aforementioned chromophores. FMO investigation revealed that DOCD2 showed the least energy gap (1.657 eV) among all the compounds with an excellent transference of charge towards the acceptor from the donor. Further, DOS pictographs and TDMs heat maps also supported FMO results, corroborating the presence of charge separation states along with efficient charge transitions. NBO analysis showed that π-linker and donors possessed positive charges while acceptors retained negative charges confirming the D–π–A architecture of the studied compounds. The λ_max values of designed chromophores (659.070–717.875 nm) were found to have broader spectra. The GRPs were also examined utilizing energy band gaps of E_HOMO and E_LUMO for the entitled compounds. Among all the derivatives, DOCD2 showed the highest values of β_tot (7.184 × 10^–27 esu) and $$\upgamma$$γ _tot (1.676 × 10^–31 esu), in coherence with the reduced band gap (1.657 eV), indicating future potentiality for NLO materials.