Wearable Sensors and Smart Devices to Monitor Rehabilitation Parameters and Sports Performance: An Overview

A quantitative evaluation of kinetic parameters, the joint’s range of motion, heart rate, and breathing rate, can be employed in sports performance tracking and rehabilitation monitoring following injuries or surgical operations. However, many of the current detection systems are expensive and designed for clinical use, requiring the presence of a physician and medical staff to assist users in the device’s positioning and measurements. The goal of wearable sensors is to overcome the limitations of current devices, enabling the acquisition of a user’s vital signs directly from the body in an accurate and non–invasive way. In sports activities, wearable sensors allow athletes to monitor performance and body movements objectively, going beyond the coach’s subjective evaluation limits. The main goal of this review paper is to provide a comprehensive overview of wearable technologies and sensing systems to detect and monitor the physiological parameters of patients during post–operative rehabilitation and athletes’ training, and to present evidence that supports the efficacy of this technology for healthcare applications. First, a classification of the human physiological parameters acquired from the human body by sensors attached to sensitive skin locations or worn as a part of garments is introduced, carrying important feedback on the user’s health status. Then, a detailed description of the electromechanical transduction mechanisms allows a comparison of the technologies used in wearable applications to monitor sports and rehabilitation activities. This paves the way for an analysis of wearable technologies, providing a comprehensive comparison of the current state of the art of available sensors and systems. Comparative and statistical analyses are provided to point out useful insights for defining the best technologies and solutions for monitoring body movements. Lastly, the presented review is compared with similar ones reported in the literature to highlight its strengths and novelties

Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors

This reprint is a collection of the Special Issue "Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors" published in Nanomaterials, which includes one editorial, six novel research articles and four review articles, showcasing the very recent advances in energy-harvesting and self-powered sensing technologies. With its broad coverage of innovations in transducing/sensing mechanisms, material and structural designs, system integration and applications, as well as the timely reviews of the progress in energy harvesting and self-powered sensing technologies, this reprint could give readers an excellent overview of the challenges, opportunities, advancements and development trends of this rapidly evolving field

Impressão 3D de sensores flexíveis baseados em polímeros para aplicações biomédicas

Flexible self-powered sensors have great potential in the medical field, offering a means of continuous monitoring of patients, helping to prevent and diagnose diseases. The present work explores biodegradable and low-cost alternatives to produce flexible sensors, from polylactic acid, for biomedical applications. Flexible sensors are composed of 3 main parts: transducers, electrodes, and substrate. In this work, the flexible sensors object of study are constituted by an incapsulating substrate of transparent adhesive tape, electrodes produced by 3D printing of a conductive composite of polylactic acid doped with carbon black and by 2 types of transducers; poly-L-lactic (PLLA) and commercial polylactic acid (PLA) To produce the poly-L-lactic acid (PLLA) and polylactic acid (PLA) transducers, two production methods were used: solvent cast and electrospinning, corona pooling methodology was used to change its electrical state. The response of sensors to mechanical and electrical stimuli was investigated and compared. The results show that both PLA and PLLA work based on the principle of piezoelectricity and triboelectricity and respond to mechanical deformation, the best results were obtained by transducers produced by solvent casting treated by corona pooling.Sensores flexíveis autoalimentados têm grande potencial no campo da medicina, podendo oferecer meios de monotorização continua de pacientes ajudando na prevenção e diagnóstico de doenças. O presente trabalho explora alternativas biodegradáveis e de baixo custo para produção de sensores flexíveis, a partir de ácido poliláctico, destinados a aplicações biomédicas. De uma forma geral os sensores flexíveis são compostos por 3 partes principais: transdutores, elétrodos e substrato, Neste trabalho os sensores flexíveis objeto de estudo são constituídos por um substrato incapsulante de fita cola transparente, elétrodos produzidos por impressão 3D de um compósito condutor de ácido poliláctico dopado com negro de fumo e por 2 tipos de transdutores; poli-L-láctico (PLLA) e ácido poliláctico (PLA). Para produzir os transdutores de ácido poli-L-láctico (PLLA) e ácido poliláctico (PLA) foram usados dois métodos de produção: solvent cast e electrospinnig e recorreu-se à metodologia de corona pooling para alteração do seu estado elétrico. A resposta dos sensores a estímulos mecânicos e elétricos foi investigada e comparada. Os resultados mostram que tanto o PLA quanto o PLLA funcionam com base no princípio da piezoeletricidade e triboeletricidade e respondem a deformação mecânica, os melhores resultados foram obtidos pelos transdutores produzidos por solvent casting tratados por corona pooling.Mestrado em Materiais e Dispositivos Biomédico

Epidermal sensors for monitoring skin physiology

Wearable sensors are revolutionizing personalised healthcare and have continuously progressed over the years in both research and commercialization. However, most efforts on wearable sensors have been focused on tracking movement, spatial position and continuous monitoring of vital signs such as heart rate or respiration rate. Recently, there is a demand to obtain biochemical information from the body using wearables. This demand stems from an individuals’ desire for improved personal health awareness as well as the drive for doctors to continuously obtain medical information for a patients’ disease management. Epidermal sensors are a sub-class of wearable sensors that can intimately integrate with skin and have the potential for monitoring physical changes as well as detecting biomarkers within skin that can be related to human health. The holy grail for these types of sensors is to achieve continuous real-time monitoring of the state of an individual and the development of these sensors are paving the way towards personalised healthcare. However, skin is highly anisotropic which makes it challenging to keep epidermal sensors in consistent contact with skin. It is important that these sensors remain in contact with skin in order to measure its electrical properties and acquire high fidelity signals. The key objective of this thesis is to develop thin conformable, stretchable epidermal sensors for tracking changes in skin physiology. The initial iteration of the screen printed epidermal sensor comprised of a flexible silver film. Impedance spectroscopy was used to understand the electrical signals generated on skin and it was used to measure relative changes due to varying water content. However, this iteration was more suited for single use. The next chapters explore different ink formulations and adherence methodologies to enhance the epidermal sensors adherence to skin. Impedance spectroscopy was used to characterise the electrical signals from these different epidermal sensor iterations, while tensile testing and on-body assessment was used to characterise its mechanical properties. The final chapter focused on investigating the use of phenyl boronic acid (PBA) functionalized hydrogels to modify the epidermal sensor with responsive hydrogel materials to enable chemical sensing of analytes relevant to skin physiology. Impedance spectroscopy was used to characterise and understand the electrical signals generated by the binding interaction of the PBA and analytes using the sensor. Overall, the work demonstrates the challenges of developing these epidermal sensors as well as presenting their potential for continuous monitoring of human skin in the future

Smart Sensors for Healthcare and Medical Applications

This book focuses on new sensing technologies, measurement techniques, and their applications in medicine and healthcare. Specifically, the book briefly describes the potential of smart sensors in the aforementioned applications, collecting 24 articles selected and published in the Special Issue “Smart Sensors for Healthcare and Medical Applications”. We proposed this topic, being aware of the pivotal role that smart sensors can play in the improvement of healthcare services in both acute and chronic conditions as well as in prevention for a healthy life and active aging. The articles selected in this book cover a variety of topics related to the design, validation, and application of smart sensors to healthcare

Simple and low-cost manufacturing of customisable drug delivery devices and flexible sensors for biomedical applications

In recent years, 3D printing technologies have been adopted into the medical and pharmaceutical industry for the fabrication of personalised medicines, oral dosage forms, medical implants, medical devices, tissue engineering applications, and many more. However, the use of 3D printing, in particular the low-cost Fused Deposition Modelling (FDM) 3D printing technique, has been limited due to the limited number of biocompatible materials suitable for pharmaceutical and biomedical applications. In this study, the FDM 3D printing technique was being explored for the fabrication of pharmaceutical products as it is the most widely available and easily accessible 3D printing technology. In order to improve the usability of FDM 3D printing for pharmaceutical and biomedical applications, the studies to fabricate several different biocompatible filaments composition that can be used for drug loading were carried out. Firstly, filaments made of several pharmaceutical grade polymers were being developed using hot-melt extrusion (HME). Three types of biocompatible polymeric filaments have been developed. They are (Polylactic Acid) PLA-based, (Hydroxypropyl Cellulose) HPC-based and (Polycaprolactone) PCL-based. These filaments were added with a plasticiser, polyethylene glycol (PEG), to improve their processability and physicochemical properties of the produced filaments so that they can used in an FDM 3D printer. The HPC-based filaments were loaded with a model drug, theophylline, that exhibits poor aqueous solubility, whereas the PCL-based filaments were loaded with a readily soluble model drug, metformin. The studies showed that the filaments were effective in sustaining the release of both drug, and the sustain release properties of the filaments can be adjusted by altering the composition of the polymers. The studies showed that the HME technology is very compatible with FDM 3D printing as it is able to produce 3D printable filaments by mixing different polymeric materials. The filaments can also be loaded with a desired drug at a required dose to allow the 3D printing of drug delivery systems. This technique allows the fabrication of personalised drug delivery systems in-house. It can be beneficial for clinics and hospitals in remote areas as the lead times can be reduced when in-house fabrication is possible. The ability to fabricate personalised medicines at hand also means that the dose can drug release patterns can be altered for the patients at any point of time when required. Apart from that, this technique can change way medicines are transported and stored, which could potentially help save cost on transportation and inventory. In addition to medicines, the FDM 3D printing technique can also be used to produce other personalised drug delivery systems such as microneedles, braces and implants of various shapes due to the flexibility of the 3D printing process. The other aspect of this research was on the fabrication of biomedical sensors that can potentially be integrated with the 3D printed drug delivery systems to form a smart drug delivery device. The idea of smart drug delivery device is that it is capable of continuous monitoring the health of a patient and then administer drug to the patient whenever it is required. The development of such smart medical devices has been one of the hottest interests in the biomedical sector. One of the main issues with such technologies is the high cost which has caused the technologies to be not so affordable for many people. Therefore, the studies to fabricate some simple biomedical sensors such as a temperature sensor and a glucose sensor using simple and cost-effective manufacturing technique were being explored. The fabrication techniques used are FDM 3D printing and a thin-film fabrication technique that involves deposition of material using a thermal evaporator. Low-cost manufacturing techniques were being explored in order to help reduce manufacturing cost which could help improve the affordability of such technologies. The fabricated temperature and glucose sensors exhibit great stability in performance and mechanical flexibility. The flexibility allows the sensors to be conformable to curved surfaces such as the skin. Hence, the sensors are suitable to be used as a wearable device or integrated into some other medical devices to form a smart medical device