Sourness is the result of high amounts of acid in foods. Citrus fruits, for example, have

Sourness is the result of high amounts of acid in foods. Citrus fruits, for example, have high amounts of citric acid, giving them their characteristic lip-puckering flavor (1, 2). However, unlike the other five tastes, researchers still don’t completely understand the mechanism behind how sour taste receptors work or why some acids result in a stronger sour flavor than others (1, 2, 3, 4). As is the case with bitterness, the detection of sour is thought to be important for survival. It can help identify foods that could be dangerous to consume, as rotten or spoiled foods often have a sour flavor due to the growth of bacteria (5, 6). In fact, many sour foods are quite nutritious and rich in plant compounds called antioxidants, which help protect your cells from damage (7, 8). While they all have a hint of sourness, the balance of sweet and sour varies greatly between different types. Citrus fruits contain a high concentration of citric acid — a naturally occurring compound found in a variety of fruits that imparts a tart, sour flavor (9). In addition to being the best natural sources of citric acid, these fruits are known for being high in vitamin C, which is essential for a str...

Bioresorbable optical sensor systems for monitoring of intracranial pressure and temperature

Continuous measurements of pressure and temperature within the intracranial, intraocular, and intravascular spaces provide essential diagnostic information for the treatment of traumatic brain injury, glaucoma, and cardiovascular diseases, respectively. Optical sensors are attractive because of their inherent compatibility with magnetic resonance imaging (MRI). Existing implantable optical components use permanent, nonresorbable materials that must be surgically extracted after use. Bioresorbable alternatives, introduced here, bypass this requirement, thereby eliminating the costs and risks of surgeries. Here, millimeter-scale bioresorbable Fabry-Perot interferometers and two dimensional photonic crystal structures enable precise, continuous measurements of pressure and temperature. Combined mechanical and optical simulations reveal the fundamental sensing mechanisms. In vitro studies and histopathological evaluations quantify the measurement accuracies, operational lifetimes, and biocompatibility of these systems. In vivo demonstrations establish clinically relevant performance attributes. The materials, device designs, and fabrication approaches outlined here establish broad f...