Location-dependent sensing of nitric oxide and calcium ions in living rat kidney using an amperometric/potentiometric dual microsensor

In this paper, we report the fabrication of a dual microsensor for sensing nitric oxide (NO) and calcium ions (Ca(2+)) and its application for simultaneous NO/Ca(2+) measurements in living rat kidney tissue. NO and Ca(2+) have very important physiological functions and are both intricately involved in many biological processes. The dual NO/Ca(2+) sensor is prepared based on a dual recessed electrode possessing Pt (diameter, 25 μm) and Ag (diameter, 76 μm) microdisks. The Pt disk surface (WE1) is electrodeposited with porous Pt black and then coated with fluorinated xerogel; and used for amperometric sensing of NO. The Ag disk surface (WE2) is chloridated to AgCl, followed by silanization and then Ca(2+) selective membrane loading; and used for potentiometric sensing of Ca(2+). The dual sensor exhibits high sensitivity of WE1 to NO (40.8 ± 6.5 pA μM(-1), n = 10) and reliable Nerntian response of WE2 to Ca(2+) changes (25.7 ± 0.5 mV pCa(-1), n = 10) with excellent selectivity to only NO and Ca(2+) over common interferents and reliable stability (up to ∼4 h tissue experiment). The prepared sensor is employed for real-time monitoring of the dynamic changes of NO and Ca(2+) levels of a rat kidney, which is induced by the administration of 10 mM l-N(G)-nitroarginine methyl ester (l-NAME, a NO synthase inhibitor). Due to the small sensor dimension, location-dependent analyses of NO and Ca(2+) are carried out at two different regions of a kidney (renal medulla and cortex). Higher NO and Ca(2+) levels are observed at the medulla than at the cortex. This study verifies the feasibility for real-time monitoring of intimately connected Ca(2+) and endogenous NO production; and also for localized concentration assessments of both NO and Ca(2+).

Adhesive RFID Sensor Patch for Monitoring of Sweat Electrolytes

Wearable digital health devices are dominantly found in rigid form factors such as bracelets and pucks. An adhesive radio-frequency identification (RFID) sensor bandage (patch) is reported, which can be made completely intimate with human skin, a distinct advantage for chronological monitoring of biomarkers in sweat. In this demonstration, a commercial RFID chip is adapted with minimum components to allow potentiometric sensing of solutes in sweat, and surface temperature, as read by an Android smartphone app with 96% accuracy at 50 mM Na(+) (in vitro tests). All circuitry is solder-reflow integrated on a standard Cu/polyimide flexible-electronic layer including an antenna, but while also allowing electroplating for simple integration of exotic metals for sensing electrodes. Optional paper microfluidics wick sweat from a sweat porous adhesive allowing flow to the sensor, or the sensor can be directly contacted to the skin. The wearability of the patch has been demonstrated for up to seven days, and includes a protective textile which provides a feel and appearance similar to a standard Band-Aid. Applications include hydration monitoring, but the basic capability is extendable to other mM ionic solutes in sweat (Cl(-), K(+), Mg(2+), NH4(+), and Zn(2+)). The design and fabrication of the patch are provided in full detail, as the basic components could be useful in the design of other wearable sensors.

System-level design of an RFID sweat electrolyte sensor patch

Wearable digital health devices are dominantly found in rigid form factors such as bracelets and pucks. An adhesive RFID sensor bandage (patch) is reported, which can be made completely intimate with human skin, a distinct advantage for chronological monitoring of biomarkers in sweat. In this demonstration, a commercial RFID chip is adapted with minimum components to allow potentiometric sensing of mM ionic solutes in sweat, and surface temperature, as read by an Android smart-phone app (in-vitro tests).

The Contributions of the Celtic Masters and Their Associates

This article summarizes the work of 4 researchers in the field of percutaneous absorption - Keith Brain, Mark Cronin, Dermot McCafferty and John Pugh. It summarizes their main achievements in this field and reviews their major contributions to the broader subject area.