This work presents an in vivo stem-mounted sensor for Nicotiana tabacum plants and an in situ cell suspension sensor for Solanum lycopersicum cells. Stem-mounted sensors are mechanically stable and less sensitive to plant and air movements than the previously demonstrated leaf-mounted sensors. Interdigitated-electrode-arrays with a dual working electrode configuration were used with an auxiliary electrode and an Ag/AgCl quasi-reference electrode. Signal amplification by redox cycling is demonstrated for a plant-based sensor responding to enzyme expression induced by different cues in the plants. Functional biosensing is demonstrated, first for constitutive enzyme expression and later, for heat-shock-induced enzyme expression in plants. In the cell suspension with redox cycling, positive detection of the enzyme β-glucuronidase (GUS) was observed within a few minutes after applying the substrate (pNPG, 4-Nitrophenyl β-D-glucopyranoside), following redox reactions of the product (p-nitrophenol (pNP)). It is assumed that the initial reaction is the irreversible reduction of pNP to p-hydroxylaminophenol. Next, it can be either oxidized to p-nitrosophenol or dehydrated and oxidized to aminophenol. Both last reactions are reversible and can be used for redox cycling. The dual-electrode redox-cycling electrochemical signal was an order of magnitude larger than that of conventional single-working electrode transducers. A simple model for the gain is presented, predicting that an even larger gain is possible for sub-micron electrodes. In summary, this work demonstrates, for the first time, a redox cycling-based in vivo plant sensor, where diffusion-based amplification occurs inside a tobacco plant’s tissue. The technique can be applied to other plants as well as to medical and environmental monitoring systems.

Chronic wounds and severe burns pose a major clinical challenge, as they often heal slowly or fail to respond to conventional treatments. In addition, there is a critical lack of tools for personalized, continuous monitoring of the healing process. Although progress has been made in both regenerative biomaterials and wearable biosensors, their integration into a unified platform that enables in situ, real‐time monitoring of wound healing remains a major challenge. Here, a multifunctional bioelectronic scaffold is introduced that enables label‐free, real‐time monitoring of cellular behavior directly on a regenerative material interface. The scaffold is fabricated by electrospinning polycaprolactone (PCL) functionalized with the bioactive, self‐assembling peptide fluorenylmethoxycarbonyl‐phenylalanine‐arginine‐glycine‐aspartic acid (Fmoc‐FRGD) to promote cell adhesion and proliferation. To enable electrical sensing, biocompatible MXene (Ti ₃ C ₂ T _X ) electrodes are conformally deposited onto the nanofibrous matrix, preserving its biological and structural properties. Using electrical impedance spectroscopy (EIS), the system provides continuous, non‐destructive readouts of cell viability, adhesion, and surface coverage. Impedance parameters extracted at low frequencies strongly correlate with biologically relevant metrics, offering a quantitative means to track cellular dynamics without additional labelling. This work establishes a foundational bioelectronic scaffold for real‐time monitoring of cell behavior, demonstrating potential for integration into regenerative therapies and advanced wound‐care systems.

Electrical impedance spectroscopy was performed on suspensions of plant cells in aqueous buffer media over a wide frequency range of 4 Hz to 20 GHz. Custom probes were designed, manufactured, and used for these investigations. Experiments were performed with a custom-made parallel plate probe and impedance analysers in the low-frequency range (4 Hz to 5 MHz), with a custom-made coaxial airline probe and a vector network analyser in the mid-frequency range (100 kHz to 3 GHz), and with a commercial open-ended probe and a vector network analyser in the high-frequency range (200 MHz to 20 GHz). The impedance data acquired were processed in order to eliminate the effects of parasitics and compensate for geometrical differences between the three probes. Following this, the data were fitted to a unified model consisting of the Randles and Debye models. The data were also normalized to a reference measurement, in order to accentuate the effects of cell concentration on the impedance of the suspensions.•The methodology allows for impedance spectroscopy of cell suspensions over a wide frequency range spanning 10 orders of magnitude.•It allows for compensation of parasitics and of geometrical variations between probes, using mathematical techniques

This paper presents the dielectric behaviour of suspensions of tomato cells (MSK8) and tobacco cells (BY2) in Murashige and Skoog, and Phosphate Buffer solutions. The behaviour of various concentrations of such suspensions is studied over a wide range of frequencies (1 kHz to 20 GHz). A distinct trend is observed in the relation between cell concentration and the capacitance of the first dispersion (i.e. at low frequencies), whilst the capacitance of the second dispersion (at medium frequencies) shows a clear relationship with the medium used. As the concentration of the cells increases, the capacitance observed increases for both cell types in both media. Furthermore, the capacitance observed for the MSK8 cells is higher than that for the BY2 cells in both media; furthermore, the normalized impedance magnitude of the MSK8 cell suspensions at low frequencies is higher than that of the equivalent normalized impedance magnitude for BY2 cells. Finally, the capacitance corresponding to the second dispersion is higher in Phosphate Buffer solution compared to that in Murashige and Skoog solution.