We present three-dimensional diffuse optical tomography of the hemodynamic response to somatosensory stimulation in a rat. These images show the feasibility of volumetrically imaging the functional response to brain activity with diffuse light. A combination of positional optode calibration and contrast-to-noise ratio weighting was found to improve imaging performance.

We introduce here a dynamic optode for buffer capacity sensing based on photochromic spiropyran (Sp). It represents the first reversible optical sensor for buffer capacity. Sensing was possible using a non-equilibrium readout mode, a novelty for photoswitchable optical ion sensors. In addition to the buffer capacity, the final point of each measurement sequence provides the pH of the solution.

A reversible and pH-independent fluorescent ion optode is introduced with an ionophore and surface confined solvatochromic dye transducer doped onto microporous nylon membranes. The resulting film responds to K+ with excellent selectivity over the range of 10-7 to 10-2 M and a response time of t95 < 60 s above 10-6 M.

Abstract Purpose Root growth, respiration, water uptake as well root exudation induce biogeochemical patterns in the rhizosphere that can change dynamically over time. Our aim is to develop a method provides complementary information on 3D system architecture and gradients around roots needed for quantitative description of processes. Methods We captured first time maize plants grown rectangula...