OLED catheters for inner-body phototherapy: A case of type 2 diabetes mellitus improved via duodenal photobiomodulation.

Phototherapeutics has shown promise in treating various diseases without surgical or drug interventions. However, it is challenging to use it in inner-body applications due to the limited light penetration depth through the skin. Therefore, we propose an organic light-emitting diode (OLED) catheter as an effective photobiomodulation (PBM) platform useful for tubular organs such as duodenums. A fully encapsulated highly flexible OLED is mounted over a round columnar structure, producing axially uniform illumination without local hotspots. The biocompatible and airtight OLED catheter can operate in aqueous environments for extended periods, meeting the essential requirements for inner-body medical applications. In a diabetic Goto-Kakizaki (GK) rat model, the red OLED catheter delivering 798 mJ of energy is shown to reduce hyperglycemia and insulin resistance compared to the sham group. Results are further supported by the subdued liver fibrosis, illustrating the immense potential of the OLED-catheter-based internal PBM for the treatment of type 2 diabetes and other diseases yet to be identified.

Simple and practical methods for utilizing parylene C film based on vertical deposition and laser patterning.

We propose two novel methods to effectively utilize parylene C films. First, we demonstrate a vertical deposition method capable of depositing a parylene C film of the same thickness on both sides of a sample. Through this method, we have formed parylene C films with a thickness of 4 µm on both sides of the sample with a thickness deviation of less than 2.5%. Further optical verification indicates that parylene C films formed by this method have a very uniform thickness distribution on each side of the surfaces. Second, we propose a debris-tolerant laser patterning method as a mask-less means to fabricate self-supporting ultrathin parylene C films. This method does not involve any photolithography and entails a simple and rapid process that can be performed using only a few materials with excellent biocompatibility. It is demonstrated that patterned parylene C films exhibit a high degree of surface uniformity and have various geometrical shapes so that they can be used for substrates of highly flexible and/or stretchable devices. Finally, we use both of the proposed methods to fabricate flexible, stretchable, and waterproof-packaged bifacial blue LED modules to illustrate their potential in emerging applications that would benefit from such versatile form factors.

Integration of Gold Nanoparticle-Carbon Nanotube Composite for Enhanced Contact Lifetime of Microelectromechanical Switches with Very Low Contact Resistance.

Electrical circuits require ideal switches with low power consumption for future electronic applications. However, transistors, the most developed electrical switches available currently, have certain fundamental limitations such as increased leakage current and limited subthreshold swing. To overcome these limitations, micromechanical switches have been extensively studied; however, it is challenging to develop micromechanical switches with high endurance and low contact resistance. This study demonstrates highly reliable microelectromechanical switches using nanocomposites. Nanocomposites consisting of gold nanoparticles (Au NPs) and carbon nanotubes (CNTs) are coated on contact electrodes as contact surfaces through a scalable and solution-based fabrication process. While deformable CNTs in the nanocomposite increase the effective contact area under mechanical loads, highly conductive Au NPs provide current paths with low contact resistance between CNTs. Given these advantages, the switches exhibit robust switching operations over 5 × 106 cycles under hot-switching conditions in air. The switches also show low contact resistance without subthreshold region, an extremely small leakage current, and a high on/off ratio.