Capacitive Sensing for Monitoring Stent Patency in the Central Airway.

Central airway obstruction (CAO) is a respiratory disorder characterized by the blockage of the trachea and/or the main bronchi that can be life-threatening. Airway stenting is a palliative procedure for CAO commonly used given its efficacy. However, mucus impaction, secretion retention, and granulation tissue growth are known complications that can counteract the stent's benefits. To prevent these situations, patients are routinely brought into the hospital to check stent patency, incurring a burden for the patient and the health care system, unnecessarily when no problems are found. In this paper, we introduce a capacitive sensor embedded in a stent that can detect solid and colloidal obstructions in the stent, as such obstructions alter the capacitor's dielectric relative permittivity. In the case of colloidal obstructions (e.g., mucus), volumes as low as 0.1 ml can be detected. Given the small form factor of the sensor, it could be adapted to a variety of stent types without changing the standard bronchoscopy insertion method. The proposed system is a step forward in the development of smart airway stents that overcome the limitations of current stenting technology.Clinical Relevance- This establishes the foundation for smart stent technology to monitor stent patency as an alternative to rutinary bronchoscopies.

Guided Heterogeneous Nucleation of Sodium Chloride at Self-Assembled Monolayer-Modified Nanoporous Gold Films.

Drug delivery devices are generally inefficient when releasing the active compound at the targeted position. In this work, we investigate nanoporous gold (np-Au) as the drug eluting device, and we use the precipitation of NaCl as a model of drug sedimentation to evaluate the patterns of solute distribution. Hydrophilic and hydrophobic modifications of np-Au result in different, but both inhomogeneous, release patterns, with most of the precipitate forming outside the device. In contrast, the fabrication of a hydrophobic-hydrophilic-layered architecture allows full penetration through the bicontinuous np-Au network, resulting in a homogeneous release pattern. Similar architectures could be used to enhance the efficacy of drug delivery.