A Segmented Cell Measuring Technique for Current Distribution Measurements in Batteries, Exemplified by the Operando Investigation of a Zn-Air Battery

A transimpedance amplifier circuit as well as an instrumental amplifier circuit were used to measure current densities of a zinc-air battery with an integrated segmented current collector foil. Error calculation showed that the transimpedance amplifier is superior to the used instrumental amplifier, but both methods provide valuable and consistent results. They both showed comparable results with operando insight into the current distribution of the battery. The knowledge about those distributions is essential to avoid fast degradation of battery materials and irreversible capacity loss due to heterogeneous dissolution of the anode during discharge. In this work we showed that oxygen starvation as well as gas flow rate leads to large current gradients. It was also demonstrated that heterogeneous current distributions on cathode side induces also a heterogenous dissolution behavior on the anode, resulting in irreversible capacity loss.

Arduino-based lab equipment: building a multipurpose pressure transducer device

BackgroundLab equipments could be expensive and their cost can be unsustainable for scientist with limited financial resources. In order to overcome these impediments and to improve our experimental studies on liver resection in rat, a multipurpose pressure measurement device was project and realized using low cost components.Materials and MethodsThe device is based on an Arduino board, an easy-to-use and open-source microcontroller, that receives analog inputs from an instrumental amplifier connected to a disposable pressure traducer. The analogic inputs are converted to digital values and an LCD can visualize the pressure values calculated from the digital inputs. Programs has been written using C++ within the Arduino IDE, while the pressure data has been recorded on PC using data-logging freeware. Calibration has been performed using a water column as standard. Measure agreement was studied by comparing this device with a water column and with a standard clinical monitoring system.ResultsThe final device it is handy and portable, it costs less the 20 euros and both the hardware and the software are easy modifiable. Calibration procedures resulted in reliable measurements as showed by the Bland-Altman measure agreement analysis.Discussion and conclusionThe final device meets the goals of the original project and offers pressure measurements that are enough accurate for our studies on liver regeneration.In a wider contest the present article shows the potentiality of the open-source-hardware movement to increase the opportunities for scientists and educators.