arXiv subjects

Sandra Ast

Publications and source records attributed to Sandra Ast.

3 recordsLinked to original sources

arXiv2017

Time-Resolved and Temperature Tuneable Measurements of Fluorescent Intensity using a Smartphone Fluorimeter

A smartphone fluorimeter capable of time-based fluorescence intensity measurements at various temperatures is reported. Excitation is provided by an integrated UV LED (370 nm) and detection obtained using the in-built CMOS camera. A Peltier is integrated to allow measurements of the intensity over T = 10 to 40 C with a maximum temperature resolution of DELTA T ~ 0.1 C. All components are controlled using a smartphone battery powered Arduino microcontroller and a customised Android application that allows sequential fluorescence imaging and quantification every DELTA t = 4 seconds. The temperature dependence of fluorescence intensity for four emitters (Rhodamine B, Rhodamine 6G, 5,10,15,20-tetraphenylporphyrin and 6-(1,4,8,11-tetraazacyclotetradecane)2-ethyl-naphthalimide) are characterised. The normalised fluorescence intensity over time of the latter chemosensor dye complex in the presence of Zn ion is observed to accelerate with an increasing rate constant, k = 1.94 min-1 at T = 15 C and k = 3.64 min-1 at T = 30 C, approaching a factor of ~ 2 with only a change in temperature of DELTA T = 15 C. Thermally tuning these twist and bend associated rates to optimise sensor approaches and device applications is proposed.

physics.ed-ph↗

arXiv2014

Intelligent smartphone-based portable network diagnostics for water security Case Study realtime pH mapping of tap water

Using a field-portable, smartphone fluorometer to assess water quality based on the pH response of a designer probe, a map of pH of public tap water sites has been obtained. A custom designed Android application digitally processed and mapped the results utilizing the GPS service of the smartphone. The map generated indicates no disruption in pH for all sites measured. All the data are assessed to fall inside the upper limit of local government regulations and are consistent with authority reported measurements. The work demonstrates a new security concept: environmental forensics utilizing the advantage of real-time analysis for the detection of potential water quality disruption at any point in the city. The concept can be extended on national and global scales to a wide variety of analytes.

physics.ins-det↗

arXiv2014

Lab-in-a-phone: Smartphone-based Portable Fluorometer for pH Field Measurements of Environmental Water

A novel portable fluorometer combining the attributes of a smartphone with an easy fit, simple and compact sample chamber fabricated using 3D printing has been developed for pH measurements of environmental water in the field. The results were then compared directly with those obtained using conventional electrode based measurements.

q-bio.QM↗