Multijet Gold Nanoparticle Inks for Additive Manufacturing of Printed and Wearable Electronics.

Conductive and biofriendly gold nanomaterial inks are highly desirable for printed electronics, biosensors, wearable electronics, and electrochemical sensor applications. Here, we demonstrate the scalable synthesis of stable gold nanoparticle inks with low-temperature sintering using simple chemical processing steps. Multiprinter compatible aqueous gold nanomaterial inks were formulated, achieving resistivity as low as ∼10-6 Ω m for 400 nm thick films sintered at 250 °C. Printed lines with a resolution of <20 µm and minimal overspray were obtained using an aerosol jet printer. The resistivity of the printed patterns reached ∼9.59 ± 1.2 × 10-8 Ω m after sintering at 400 °C for 45 min. Our aqueous-formulated gold nanomaterial inks are also compatible with inkjet printing, extending the design space and manufacturability of printed and flexible electronics where metal work functions and chemically inert films are important for device applications.

Plasma-jet printing of colloidal thermoelectric Bi2Te3 nanoflakes for flexible energy harvesting.

Thermoelectric generators (TEGs) convert temperature differences into electrical power and are attractive among energy harvesting devices due to their autonomous and silent operation. While thermoelectric materials have undergone substantial improvements in material properties, a reliable and cost-effective fabrication method suitable for microgravity and space applications remains a challenge, particularly as commercial space flight and extended crewed space missions increase in frequency. This paper demonstrates the use of plasma-jet printing (PJP), a gravity-independent, electromagnetic field-assisted printing technology, to deposit colloidal thermoelectric nanoflakes with engineered nanopores onto flexible substrates at room temperature. We observe substantial improvements in material adhesion and flexibility with less than 2% and 11% variation in performance after 10 000 bending cycles over 25 mm and 8 mm radii of curvature, respectively, as compared to previously reported TE films. Our printed films demonstrate electrical conductivity of 2.5 × 103 S m-1 and a power factor of 70 µW m-1 K-2 at room temperature. To our knowledge, these are the first reported values of plasma-jet printed thermoelectric nanomaterial films. This advancement in plasma jet printing significantly promotes the development of nanoengineered 2D and layered materials not only for energy harvesting but also for the development of large-scale flexible electronics and sensors for both space and commercial applications.

High-Performance Flexible Bismuth Telluride Thin Film from Solution Processed Colloidal Nanoplates.

Thermoelectric generators are an environmentally friendly and reliable solid-state energy conversion technology. Flexible and low-cost thermoelectric generators are especially suited to power flexible electronics and sensors using body heat or other ambient heat sources. Bismuth telluride based thermoelectric materials exhibit their best performance near room temperature making them an ideal candidate to power wearable electronics and sensors using body heat. In this report Bi2Te3 thin films are deposited on a flexible polyimide substrate using low-cost and scalable manufacturing methods. The synthesized Bi2Te3 nanocrystals have a thickness of 35 ± 15 nm and a lateral dimension of 692 ± 186 nm. Thin films fabricated from these nanocrystals exhibit a peak power factor of 0.35 mW/m·K2 at 433 K, which is among the highest reported values for flexible thermoelectric films. In order to evaluate the flexibility of the thin films, static and dynamic bending tests were performed while monitoring the change in electrical resistivity. After 1000 bending cycles over a 50mm ROC, the change in electrical resistance of the film was 23%. Using our Bi2Te3 solutions, we demonstrated the ability to print thermoelectric thin films with an aerosol jet printer, highlighting the potential of additive manufacturing techniques for fabricating flexible thermoelectric generators.

Resistin and Plasma-reactive Oxygen Metabolite Levels in Obese and Non-obese Individuals with Chronic Periodontitis in Response to Non-surgical Periodontal Therapy.

AIM: To assess and compare the impact of non-surgical periodontal therapy on plasma reactive oxygen metabolites and resistin values in chronic periodontitis obese and non-obese patients. MATERIALS AND METHODS: Total 200 subjects were included in the present study and were broadly divided into two study groups with 100 patients in each group as follows: group A: Obese patients with chronic periodontitis, group B: Non-obese, normal weight patients with chronic periodontitis. Various following periodontal parameter were calculated at the baseline time and two months after the non-surgical periodontal therapy. Plasma reactive oxygen metabolite (RM) and serum and GCF resistin levelswere evaluated. Assessment of all the results was done by Statistical Package for Social Sciences (SPSS) software. RESULTS: Significant results were obtained while doing an inter-group comparison of clinical attachment levels between two study groups. Significant results were obtained while comparing the clinical attachment levels in both the study groups at different time intervals. Significant 9 reduction in the RM was seen in Group B subjects in comparison to Group A subjects 2 months after non-surgical periodontal therapy. CONCLUSION: In patients with chronic periodontitis, obesity can be considered as an important factor in the alteration of resistin levels. CLINICAL SIGNIFICANCE: Obese patients should be motivated for reducing weight so that periodontal therapy and other treatment modalities could be carried out more effectively.

High-performance and flexible thermoelectric films by screen printing solution-processed nanoplate crystals.

Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate a peak ZT of 0.43 along with superior flexibility, which is among the highest reported ZT values in flexible thermoelectric materials. A flexible thermoelectric device fabricated using the printed films produces a high power density of 4.1 mW/cm(2) with 60 °C temperature difference between the hot side and cold side. The highly scalable and low cost process to fabricate flexible thermoelectric materials and devices demonstrated here opens up many opportunities to transform thermoelectric energy harvesting and cooling applications.