Mass transport limitations for electrochemical sensing in low-flux excretory fluids

Pulse Power Generation Chronoamperometry as an Advanced Readout for (Bio)sensors: Application for Noninvasive Diabetes Monitoring

“…Accordingly, an important challenge concerns the accuracy of the (bio)­sensing system. Actually, in some cases, the signal attributed to the sweat metabolite variations in time seems to be comparable with the noises of the on-body device as well as the possible background signal fluctuations. , It is also worth mentioning that the sweating rate varies over an order of magnitude for a single human (∼0.01–0.1 mL·cm –2 ·h –1 ) and strongly depends on physical activity, stimulation of glands, temperature, electrolyte balance, etc. ,, At the same time, an electrochemical biosensor response can strongly depend on the hydrodynamic conditions, making it tricky to discriminate the metabolite concentration and sweat rate impacts …”

“…A high-precision multilayer printed circuit board (PCB) was manufactured. The components were assembled using a Quad Flat No-lead (QFN) and surface mounted device (SMD) technologies in the factory, giving final dimensions of the board of 20 × 20 mm, an assembled device size of 39 × 35 × 10 mm, and a weight of 11 g, including the case, battery, and sweat collector. , The microcontroller firmware and Android application were developed using free and open-source software and packages. For the on-skin tests (including remote continuous monitoring with several devices), an UMKA-P interface was integrated into the flow-through exchangeable sensor casing produced using high-resolution optical three-dimensional (3D) printing with a FormLabs Form 2 3D printer and Formlabs Tough photopolymer resin (Formlabs).…”

“…16,18,23 At the same time, an electrochemical biosensor response can strongly depend on the hydrodynamic conditions, making it tricky to discriminate the metabolite concentration and sweat rate impacts. 24 Earlier, to improve the accuracy of PB-based biosensors, we suggested the so-called power generation mode, providing their nearly noiseless operation. 25 Short-circuiting Prussianblue-modified electrode with Ag|AgCl reference provides operation of the redox electrocatalyst close to its optimal potential (around 0.00 V versus Ag|AgCl).…”

“…Equipment. To realize a pulse regime with a millisecond readout, an UMKA-P 24 (Universal Monitor Kit-Ammeter operated in Pulse mode) was used. The electronic core of the device consisted of an LMP91000 Analog-Front-End chip and an NRF52832 microcontroller with built-in Bluetooth lowenergy support.…”

Bioengineered Lactate Oxidase Mutants for Enhanced Electrochemical Performance at Acidic pH

“…The selected residues were mutated in silico , and the coordinate files for wild‐type and mutants were minimized in Chimera using the Amber ff99SB forcefield, by applying 5000 steepest descent steps and 5000 conjugated gradient steps. The resulting structures were then analyzed in the ROSIE pKa server [51] to calculate pKa of the His 265. Those mutants showing calculated pKa values below 6 were selected for production and experimental characterization.…”