Investigation of nanomaterials in the wearable electronics for health monitoring

Physiological signals contain a wealth of personal health information which needs continuous monitoring for early detection of disease-induced physiological irregularities and can be established as a potential approach to developing personalized healthcare devices. It has a very urgent need for the development of a new generation of convenient, low cost, reliable, and stable wearable devices to keep track on such critical signals in case of the firsthand notice of any abnormal changes indicating the pathological changes in our body.In the past decades, various categories of wearable sensors and platforms have been developed targeting the continuous, on-demand recordings of wide ranges of signals by different fabrication methods. Additive Manufacturing, also named three-dimensional (3D) printing has been developed in the past few years and received tremendous interest. It enables distributed manufacturing, allowing users to easily produce customized 3D objects in office or at home. In addition, additive manufacturing allows to reduce the production waste and energy consumption and possesses great potential to replace the conventional clean-room based fabrication technology with the potential of circumventing the requirement of sophisticated equipment and highly trained specialists. Moreover, it offers a broader range of material selection, and allows customization of the desired ink for different application purposes. Here, in this thesis, a series of application of 3D printing technology with different home developed nanomaterials in the development of the next generation of the wearable sensing platforms have been studied. In the first study, the physics behind the 3D printing process has been detailed analyzed and quantified the relationship between the different printing parameters to the final printed resolution. It helps the improvement of the reliability of the fabrication process by eliminating the unreliable trial and error method to optimize the required printing parameters. In the second study, an all-3D printed pressure sensor has been developed for radial artery pulse monitoring. Taking the advantaged of the material selection and preparation, all the ink shows good printability and strong mechanical properties. In addition, by carefully managing the printing path, direct 3D printed micropattern has been generated to enhance the sensor’s performance for subtle pressure detection. At last, the proposed all 3D printed pressure sensor exhibits high sensitivity and good mechanical property while mounting on human body, achieving reliable real-time biosignal recording. In the last study, a novel integrated sensing platform has been proposed. A triboelectric nanogenerator has been introduced as the power supply to remove the need of the battery, eliminating the potential drawbacks of the battery charging, replacement, and safety concerns. By careful selection of the materials, the two-dimensional (2D) MXene turns out to be the proper material satisfied the requirement of the conductivity, triboelectricity, and the extrusion printing capability. The performance of the 3D printed triboelectric nanogenerator has been well characterized, and the integrated sensing platform with the pressure sensor has been successfully demonstrated. Furthermore, a LED illustrator and an NFC antenna are added to the entire sensing platform to enable the direct visualization of the signal and real-time waveform recording. To the best of our knowledge, it is the first report of a wearable system for continuous and real-time physiological biosignals monitoring fully powered by human motion, signaling exciting potential in the field