Neurological diseases are a prevalent cause of global mortality and are of growing concern when considering an ageing global population. Traditional treatments are accompanied by serious side effects including repeated treatment sessions, invasive surgeries, or infections. For example, in the case of deep brain stimulation, large, stiff, and battery powered neural probes recruit thousands of neurons with each pulse, and can invoke a vigorous immune response. This paper presents challenges in engineering and neuroscience in developing miniaturized and biointegrated alternatives, in the form of microelectrode probes. Progress in design and topology of neural implants has shifted the goal post toward highly specific recording and stimulation, targeting small groups of neurons and reducing the foreign body response with biomimetic design principles. Implantable device design recommendations, fabrication techniques, and clinical evaluation of the impact flexible, integrated probes will have on the treatment of neurological disorders are provided in this report. The choice of biocompatible material dictates fabrication techniques as novel methods reduce the complexity of manufacture. Wireless power, the final hurdle to truly implantable neural interfaces, is discussed. These aspects are the driving force behind continued research: significant breakthroughs in any one of these areas will revolutionize the treatment of neurological disorders.

Neuromodulation is of great importance both as a fundamental neuroscience research tool for analyzing and understanding the brain function, and as a therapeutic avenue for treating brain disorders. Here, an overview of conceptual and technical progress in developing neuromodulation strategies is provided, and it is suggested that recent advances in nanotechnology are enabling novel neuromodulation modalities with less invasiveness, improved biointerfaces, deeper penetration, and higher spatiotemporal precision. The use of nanotechnology and the employment of versatile nanomaterials and nanoscale devices with tailored physical properties have led to considerable research progress. To conclude, an outlook discussing current challenges and future directions for next‐generation neuromodulation modalities is presented.

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The human eye contains multiple biomarkers related to various diseases, making electronic contact lens an ideal non-invasive platform for their diagnosis and treatment. Recent advances in technology have enabled the monitoring and diagnosis of glaucoma from Intraocular Pressure (IOP) detection, diabetes from glucose concentration detections, and other biosensors for pH and temperature sensing. Different sensor designs have led to distinct power transfer techniques, among which inductively coupled power transfer is considered most favourable for electronic contact lenses power delivery applications. Therefore, loop antenna, spiral shape antenna, and antenna with nanomaterials such as graphene and hybrid silver nanofibers have been explored under Industrial, Scientific, and Medical (ISM) frequency bands for both Wireless Power Transfer (WPT) and data communication. Notably, spiral antennas are also considered as the component of IOP sensing using capacitive sensors to detect the changes in frequency caused by pressure. This article reviews the stateof-the-art technologies in electronic contact lens sensors and their power delivery techniques. Herein, diverse sensing methods, materials, and power transfer techniques and the promising future trends and challenges in electronic contact lenses have been presented.

Magnetoelectric devices are readily employed as sensors, actuators, and antennas, but typically exhibit low power output. This paper presents considerations for the viability of magnetoelectric composites for wireless power transfer in neural implantation. This is accomplished herein by studying different types of biocompatible encapsulants for magnetoelectric devices, their impact on the output voltage of the composites, and the rigidity of the materials in the context of tissue damage. Simulation results indicate that a polymer encapsulant, rather than creating a substrate clamping effect, increases the voltage output of the magnetoelectric, which can be further improved by careful polymer selection. These attributes are modelled using the finite element method (FEM) with COMSOL Multiphysics. The addition of a 0.2 mm poly(ethyl acrylate) encapsulating layer increases the piezoelectric voltage to 3.77 V AC output at a magnetic field strength of 200 Oe, as the magnetostrictive layer deforms inside the flexible outer polymer. Comparing voltage conditioning circuits, the output is sufficient for low-voltage neuronal stimulation when employing a simple bridge rectifier which boasts minimal charging time and ripple voltage lower than 1 mV.