An electronic skin (e-skin) for the next generation of robots is expected to have biological skin-like multimodal sensing, signal encoding, and preprocessing. To this end, it is imperative to have high-quality, uniformly responding electronic devices distributed over large areas and capable of delivering synaptic behavior with long- and short-term memory. Here, we present an approach to realize synaptic transistors (12-by-14 array) using ZnO nanowires printed on flexible substrate with 100% yield and high uniformity. The presented devices show synaptic behavior under pulse stimuli, exhibiting excitatory (inhibitory) post-synaptic current, spiking rate-dependent plasticity, and short-term to long-term memory transition. The as-realized transistors demonstrate excellent bio-like synaptic behavior and show great potential for in-hardware learning. This is demonstrated through a prototype computational e-skin, comprising event-driven sensors, synaptic transistors, and spiking neurons that bestow biological skin-like haptic sensations to a robotic hand. With associative learning, the presented computational e-skin could gradually acquire a human body–like pain reflex. The learnt behavior could be strengthened through practice. Such a peripheral nervous system–like localized learning could substantially reduce the data latency and decrease the cognitive load on the robotic platform.

The unresolved and paramount challenge in bio-imaging and targeted therapy is to clearly define and demarcate the physical margins of tumor tissue. The ability to outline the healthy vital tissues to be carefully navigated with transection while an intraoperative surgery procedure is performed sets up a necessary and under-researched goal. To achieve the aforementioned objectives, there is a need to optimize design considerations in order to not only obtain an effective imaging agent but to also achieve attributes like favorable water solubility, biocompatibility, high molecular brightness, and a tissue specific targeting approach. The emergence of near infra-red fluorescence (NIRF) light for tissue scale imaging owes to the provision of highly specific images of the target organ. The special characteristics of near infra-red window such as minimal auto-fluorescence, low light scattering, and absorption of biomolecules in tissue converge to form an attractive modality for cancer imaging. Imparting molecular fluorescence as an exogenous contrast agent is the most beneficial attribute of NIRF light as a clinical imaging technology. Additionally, many such agents also display therapeutic potentials as photo-thermal agents, thus meeting the dual purpose of imaging and therapy. Here, we primarily discuss molecular imaging and therapeutic potentials of two such classes of materials, i.e., inorganic NIR dyes and metallic gold nanoparticle based materials.

The ion‐sensitive field effect transistors (ISFETs), proposed little over 50 years ago, today make the most promising devices for lab‐on‐a‐chip, implantable, and point‐of‐care (POC) diagnostics. Their compatibility with CMOS (Complementary Metal Oxide Semiconductor) technology and the low cost through mass production have been the driving factors so far. Nowadays, they are also being developed in flexible form factors for new applications such as wearables and to improve the effective usage in existing applications such as implantable systems. In this regard, the CMOS ultra‐thin chip (UTC) technology and the bonding by printing are the noteworthy advances. This paper comprehensively reviews such new developments in the CMOS‐compatible ISFETs, along with their theory, readout circuitries, circuit‐based techniques for compensation of the ISFET's instabilities, such as the offset, flicker noise, and drift. The sensing mechanisms and the properties of interface between the electrolyte under test and the metal‐oxide based ion‐sensitive electrodes have been discussed along with a brief overview of the metal‐oxide based pH sensors. An overview of the reported mechanically flexible pH sensors, including ISFETs, is provided and the history of ISFET applications are also covered. Finally, established models that can be used to design flexible circuits are presented, and possible opportunities to use circuit techniques to compensate for mechanical deformation are discussed.

Piezoceramics have been the common choice for sensing applications, however their integration with other electronics is limited due to their large size. Also, environmental concerns have been limiting the use of ceramics due to their lead content, toxic for humans. Piezoelectric crystalline thin films have arisen as alternative materials offering compatibility with miniaturization and integrated processes, though their piezoelectric properties are low (d₃₃ < 15 pC N⁻¹) compared to ceramics (d₃₃ > 300 pC N⁻¹), hindering their applicability. Several methods have been studied aiming to improve the piezoelectric output of thin films, including doping or the less investigated inclusion of porosity. However, they all require complex techniques that increase the cost. In this work, a giant electromechanical d₃₃ coefficient of 115.6 pC N⁻¹ has been obtained inducing porosity in inclined ZnO thin films via oblique angle deposition, which is beyond record values reported for doped ZnO thin films and an order of magnitude higher than standard ZnO thin films (11.6 pC N⁻¹). Morphology, composition, crystal structure, porosity, and piezoelectricity are reported for standard and inclined films. Finite element simulations have been carried out to investigate the performance of the piezoelectric‐enhanced thin films in an ultrasonic pulse‐echo setup.

This paper presents ISFET array based pH-sensing system-on-ultra-thin-chip (SoUTC) designed and fabricated in 350 nm CMOS technology. The SoUTC with the proposed current-mode active-pixel ISFET circuit array is desined to operate at 2 V and consumes 6.28 μW per-pixel. The presented SoUTC exhibits low sensitivity to process, voltage, temperature and strain-induced (PVTS) variations. The silicon area occupancy of each active-pixel is 44.9 × 33.5 µm ² with an ion-sensing area of 576 µm ² . The design of presented ISFET device is analysed with finite element modeling in COMSOL Multiphysics using compact model parameters of MOSFET in 350 nm CMOS technology. Owing to thin (∼30 µm) Si-substrate the presented SoUTC can conform to curvilinear surfaces, allowing intimate contact necessary for reliable data for monitoring of analytes in body fluids such as sweat. Further, it can operate either in a rolling shutter fashion or in a pseudo-random pixel selection mode allowing the simultaneous detection of pH from different skin regions. Finally, the circuits have been tested in aqueous Dulbecco's Modified Eagle Medium (DMEM) culture media with 5–9 pH values, which mimics cellular environments, to demonstrate their potential use for continuous monitoring of body-fluids pH.

We report a deposition pathway for barium titanate (BTO) onto hydrophobically coated cobalt ferrite (CFO) nanoparticles, resulting in the formation of magnetoelectric core–shell nanoparticles. Our strategy utilizes a bimetallic Ba and Ti oleate (BTOle) precursor, which hydrophobically interacts with dimethyl­dioctadecyl­ammonium bromide (DDAB)-stabilized CFO particles during an interfacial phase transfer step. Thermal post-treatment yields a crystalline structure comprising distinguishable BTO and CFO phases, with BTO adopting a distorted cubic to tetragonal crystal phase. Magnetoelectric characterization yields a millivolt voltage-range output associated with the mechanical coupling between the piezoelectric and magnetostrictive phases. This method circumvents traditional sol–gel limitations and phase transfer hurdles, offering a streamlined route for fabricating magnetoelectric nanoparticles. Our results suggest magnetoelectric particles are suitable for incorporation in wireless actuation technologies.