Christian Albertus Nijhuis

Naturally occurring magnetotactic bacteria have an inherent ability to sense and align to earth's geomagnetic field due to the presence of magnetosomes—membranous microstructures containing iron oxide nanoparticles. These functionalities can be exploited for tuning movements and guided spatial patterning in controlled magnetic field. While being arduous to culture in laboratories, these organisms have complex genetic make‐up with tight regulation on their magnetosome synthesis. Inspired by the magnetotactic bacteria, we aim to render magnetic behavior to E. coli . We mimic the magnetosomes in magnetotactic bacteria by employing a membraneless proteinaceous compartment from the thermophilic iron storage protein, ferritin, fused with a magnetite‐forming peptide, m6A. To enhance iron accumulation, the E. coli iron metabolism is engineered by tailoring the expression of iron influx and efflux genes. Numerical simulations support our observations of a highly responsive magnetic E. coli . This study presents a strategy to engineer magnetic response in E. coli which can be adopted to other bacteria.

Electrochemiluminescence (ECL) is a powerful sensing technique but typically relies on liquid electrolytes and multi-electrode configurations, limiting device miniaturization and integration. Here, we report a solid-state electrochemically driven luminescent sensing platform based on two-electrode junctions comprising an indium tin oxide bottom electrode, a Ru(bpy)32+−TPrA@Nafion active layer (TPrA: tripropylamine), and a soft eutectic gallium−indium (EGaIn) top electrode. Nafion serves as a porous host matrix that immobilizes the luminophore and co-reactant while facilitating analyte uptake, whereas EGaIn provides a simple conformal electrical contact for solid-state operation. Despite the absence of a liquid electrolyte during electrical excitation, the junctions retain key characteristics of classical Ru(bpy)32+ electrochemistry. The luminescence is enhanced by the co-reactant TPrA and quenched by dopamine (DA), enabling quantitative sensing based on modulation of the emission intensity. The platform exhibits a linear response to dopamine over a concentration range of 1.0 × 10−10−1.0 × 10−4 M with a detection limit of 5.1 × 10−11 M, together with excellent reproducibility, selectivity, operational stability, and satisfactory recovery in human serum samples. These results demonstrate that ECL-inspired sensing chemistry can be implemented in a solid-state device architecture, providing a promising strategy for integrated luminescent sensing platforms and miniaturized analytical devices.

When all junction components, including the anchoring group, electrode materials, and molecule–electrode contact, are kept unchanged, changing only the number of molecular repeat units can induce oscillatory conductance, known as the odd–even effect. This effect is viewed as a manifestation of molecular backbone parity. However, whether such parity‐dependent charge transport is intrinsically encoded by the molecular backbone or governed by molecule–electrode interfacial coupling remains unclear. Here, we show that interfacial coupling can program the odd–even conductance trend in molecular junctions. Molecules with odd‐numbered repeat units exhibit higher conductance than their even‐numbered homologues when coupled to EGaIn/Ga ₂ O ₃ electrodes through physical van der Waals interactions. Strikingly, this trend is reversed when strong thiol–Ag chemical bonds dominate the junction interface, while replacing thiol with a weaker amino chemical anchor nearly eliminates the odd–even effect. Beyond conductance, we demonstrate that the formation probability of molecule‐bridged junctions also exhibits a pronounced odd–even effect. Assisted by DFT‐based calculations, we clarify the underlying mechanism, thereby establishing interfacial coupling as a design principle for programming charge transport and improving the formation yield of molecule‐based devices.

The efficiency of organic electronic devices relies on application of organic gate dielectric materials. Such organic films should exhibit high chemical/thermal stability, aromatic functionality compatible with organic semiconductors, and low gate leakage currents in combination with low thickness to reduce the operating voltage. An interesting class of materials for such applications are self‐assembled monolayers (SAMs) among which the N ‐heterocyclic carbenes (NHC) are known for their high chemical/thermal stability. The conductivity of NHC SAMs, however, has been sparsely explored and their electrical properties remain controversial. Here we report conductivity analysis for a well‐defined series of aromatic NHC SAMs. Our data show that all analyzed monolayers are highly insulating and in particular the shortest possible NHC of just ∼3.3 Å is by 5 orders of magnitude more insulating than standard insulators based on alkanethiolate SAM of the same length. Our calculations indicate the absence of destructive quantum interference (DQI) effect which has been considered responsible for suppression of conductivity in aromatic molecules. The suppression of SAMs conductivity just via selection of the imidazolium‐based bonding group is conceptually simpler opening possibility of using NHC SAMs as an ultra‐thin, and exceptionally insulating, aromatic monolayers for functionalization of the gate electrodes.

The efficiency of organic electronic devices relies on application of organic gate dielectric materials. Such organic films should exhibit high chemical/thermal stability, aromatic functionality compatible with organic semiconductors, and low gate leakage currents in combination with low thickness to reduce the operating voltage. An interesting class of materials for such applications are self‐assembled monolayers (SAMs) among which the N ‐heterocyclic carbenes (NHC) are known for their high chemical/thermal stability. The conductivity of NHC SAMs, however, has been sparsely explored and their electrical properties remain controversial. Here we report conductivity analysis for a well‐defined series of aromatic NHC SAMs. Our data show that all analyzed monolayers are highly insulating and in particular the shortest possible NHC of just ∼3.3 Å is by 5 orders of magnitude more insulating than standard insulators based on alkanethiolate SAM of the same length. Our calculations indicate the absence of destructive quantum interference (DQI) effect which has been considered responsible for suppression of conductivity in aromatic molecules. The suppression of SAMs conductivity just via selection of the imidazolium‐based bonding group is conceptually simpler opening possibility of using NHC SAMs as an ultra‐thin, and exceptionally insulating, aromatic monolayers for functionalization of the gate electrodes.

We report a robust redox‐active N‐heterocyclic carbene (NHC) monolayer that exhibits synapse‐like behavior driven by proton‐coupled electron transfer (PCET). Our quinone‐functionalized NHC (Rex–NHC) forms densely packed, upright self‐assembled monolayers (SAMs) on Au, confirmed by cyclic voltammetry, x‐ ray photoelectron spectroscopy, sum‐frequency generation spectroscopy, and infrared reflection absorption spectroscopy. Molecular junctions built as Au–Rex–NHC//Ga ₂ O ₃ /EGaIn operate over ± 2 V and can withstand electric fields up to 3.3 GV/m. Bias‐induced PCET toggles between quinone (off) and hydroquinone (on) states, yielding reversible hysteresis with on/off ratios up to 1.9 × 10 ² . The devices exhibit spike‐timing and spike‐rate‐dependent plasticity, demonstrating for the first time molecular‐level neuromorphic behavior using NHCs as anchoring groups.

Self-sustained oscillations arise from coupled electrochemical and mechanical processes in GaIn-droplet systems. Asymmetric contraction and electrowetting-induced Marangoni flow sequentially drive the droplet away from and back toward the electrode.

Every year, tens of million tons of electronic waste (e-waste) are generated globally. E-waste recycling is urgent but hampered by key bottlenecks in metal recovery, such as material complexity, harmful emissions, high energy consumption, and infrastructure limitations. We address this challenge by recycling e-waste based on a liquid metal alloy of eutectic gallium-indium (EGaIn). We introduce a sustainable technique and protocol for printing flexible electronics using recycled EGaIn. A low-cost setup is developed for widespread use, paving the way for home-made metallic electronics and in-house recycling as a possible pathway to improve sustainability.

Self-oscillators are intriguing due to their ability to sustain periodic motion without periodic stimulus. They remain rare as achieving such behavior requires a balance of energy input, dissipation and non-linear feedback mechanism. Here, we report a molecular-scale optoelectronic self-oscillatory system based on electrically excited plasmons. This system generates light via inelastic electron tunnelling, where electrons lose their energy to molecules and excite the surface plasmon polaritons that decay radiatively. Time-series imaging of photon emission in gold-naphthalene-2-thiol-EGaIn junctions, together with correlation mapping of individual emission spots, reveal long-lived (~1000 s), low-frequency oscillations (1-20 mHz) interspersed with transient high-frequency (20-200 mHz) bursts. This behavior can be explained by attributing individual emission spots to single-molecule resistors that follow Kirchhoff's circuit laws. Induced by tunnelling current, these individual spots emit in a correlated way, self-sustaining the overall oscillatory emission from the whole junction. Our observation is of great interest as it resonates with a broader understanding of similar molecular-scale dynamic systems such as picocavities, offering exciting potential for optoelectronic and sensing applications.