Synthesis and photonic sintering of bioresorbable zinc nanoparticle ink for transient electronics manufacturing

Zinc is an essential \u27trace element\u27 that supports immune systems, and is required for DNA synthesis, cell division, and protein synthesis. Zinc nanoparticles (Zn NP) has antibacterial properties and potential to be used in biodegradable printed electronics devices. The research presented here is about the synthesis of Zn NP and their potential use in transient electronics devices. In Paper 1, a technique of room temperature synthesis of Zn NP is reported using ball milling. Controlled amount of PVP was mixed in the solvent to stabilize the Zn particles and minimize cold welding during milling. The size of the produced Zn NPs was found to be heavily dependent on the amount of PVP used in the solvent. The analyses reveals a crystal size of ~34.834 ± 1.76 nm and very low oxidation in the Zn NPs. The obtained Zn NPs were directly used to print bioresorbable patterns on Na-CMC and PVA substrates which forms conductive patterns upon subjecting to photonic sintering. In paper 2, a new method of manufacturing transient electronics devices is reported. An aerosol printer has been used to print patterns using Zn NPs based bioresorbable ink. Lower concentration of PVP used results in the formation of surface oxide, while higher concentration of PVP hinders the coalescence of Zn NPs. Conductivity of about 0.1% to that of bulk has been found when 0.1 wt % PVP is used. Analytical simulations has been accompanied with experimental verifications in the study of sintering mechanism of Zn NPs. XPS analysis indicates Zn NP surface protection by PVP. The ink was used to print patterns which can potentially be used as RFID tags, on a biodegradable Na-CMC substrate. The whole substrate dissolves in water --Abstract, page iv

An early gene of the flavonoid pathway, flavanone 3-hydroxylase, exhibits a positive relationship with the concentration of catechins in tea (Camellia sinensis)

Tea (Camellia sinensis (L.) O. Kuntze) leaves are a major source of flavonoids that mainly belong to the flavan 3-ols or catechins. Apart from being, responsible for test duality. these compounds have medicinal properties. Flavanone 3-hydroxylase (F3H) is an abundant enzyme in tea leaves that catalyzes the stereospecific hydroxylation of (2S)-naringenin to form (2R.3R)-dihdrokaempferol. We report full-length cDNA sequence of F3H from tea (CsF3H Accessionno. AY641730). CsE3H comprised 1365 by with an open reading frame of 1107 it (from 43 to 1149) encoding a polypeptide of 368 amino, acids. Expression of CsF3H in an expression vector in Escherichia coli yielded a frictional protein with a specific activity of 32 nmol min(-1) mg protein(-1). There was a positive correlation between the concentration of catechins and CsF3H expression in leaves of different developmental stages. CsF3H expression was clown-regulated in response to drought, abscisic acid and gibberellic acid treatment, but up-regulated in response to wounding. The concentration of catechins paralleled the expression data. Exposure of tea shoots to 50-100 mu M catechins led to down-regulation of CSF3H expression suggesting substrate mediated feedback regulation of the gene. The strong correlation between the concentration of catechins and CsF3H expression indicates a critical role of F3H in catechin biosynthesis

Epidermal Wireless Sensors on Releasable Films for Biophysical Signal Measurement on Facial Areas

This paper presents an ultrathin stretchable device capable of soft lamination onto the skin with a releasable film for wireless measurement of biophysiological signal on skin. The device contains metallic electrodes and graphite strips, and can be attached to multiple skin locations in a conformal manner. Experimental results demonstrate that the device offers ease of skin releasing with reliable biopotential and strain measurement capability. This device when combined with other sensing mechanisms can yield a comprehensive sleep evaluation system capable of revealing influencing factors that are specific to a person, allowing highly individualized treatment plans for patients with sleep disorders

Aerosol Printing and Photonic Sintering of Bioresorbable Zinc Nanoparticle Ink for Transient Electronics Manufacturing

Bioresorbable electronics technology can potentially lead to revolutionary applications in healthcare, consumer electronics, and data security. This technology has been demonstrated by various functional devices. However, majority of these devices are realized by CMOS fabrication approaches involving complex and time-consuming processes that are high in cost and low in yield. Printing electronics technology represents a series of printing and post processing techniques that hold promise to make high performance bioresorbable electronics devices. But investigation of printing approaches for bioresorbable electronics is very limited. Here we demonstrate fabrication of conductive bioresorbable patterns using aerosol printing and photonic sintering approaches. Experimental results and simulation reveals that ink compositions, photonic energy, film thickness, and ventilation conditions may influence the effect of photonic sintering. A maximum conductivity of 22321.3 S/m can be achieved using 1 flash with energy of 25.88 J/cm2 with duration of 2 ms. By combining two cascaded sintering procedures using flash light and laser further improve the conductivity to 34722.2 S/m. The results indicate that aerosol printing and photonic sintering can potentially yield mass fabrication of bioresorbable electronics, leading to prevalence of printable bioresorbable technology in consumer electronics and biomedical devices