For analytical chemistry applications, the microfluidic devices often need to be interfaced to a sensor, such as a spectrometer, an optical or an electronic sensor or even radiation detectors. The microfluidic device becomes a flow cell for reagent and sample delivery. Here are few examples.
Flow cells for dye doped leaky waveguide (DDLW) sensors. In collaboration with Dr Ruchi Gupta at the Univerity of Birmingham in the UK we have developed a range of flow cells in black PMMA that sit atop a chitosan waveguide material. These have been applied for a sensing of biomarkers such as ferritin, thrombin and VEGF. [N Alamrani et al., Analyst, 2019, 144, 6048.]
Flow cells for screen printed electrodes. We have designed a range of microfluidic flow cells to hold disposable screen printed electrodes, for example DropSens electrodes. These chips have been employed for on-chip analysis of carbohydrate-based radiotracers [L Patinglag et al., Analyst, 2020,145, 4920] and for immunosensing of ferritin [M Garg et al., Biosensors, 2020, 10, 91.] The magnets in this chip allows for easy replacement of the electrode, reducing downtime and increasing efficiency.
Microfluidic devices for spectroscopy. Using a chip with a channel cut through the middle allows for suitable path lengths for spectroscopy. This has been proven to work with optical clarity and pH determination. Fibre cables are used to transmit and receive light, allowing for spectroscopic method to be straightforwardly changed. [MD Tarn et al., MicroTAS 2014.]
Microfluidic radiation detection. The interactions between silicon photomultipliers (SiPMs) and positrons allows radiation levels to be measured. The winding passage allows the full area of the SiPM to be fully exposed to radioactivity from a known volume of radiotracer. This method has been used to determine radiochemical identitiy by measuring half life and comparing it to known values as well as measuring activity levels. [MP Taggart et al., Lab Chip, 2016, 16, 1605.]
Scintillator-based radiation detection. We have designed a chip with a bottom layer consisting of a plastic scintillator seated on a SiPM. This has been tested with 18F samples to simulate 18F-FDG detection as part of a radioHPLC system. Such a procedure allows real time detection of radiotracers in clinically relevant concentrations while needing less space than conventional radio-HPLC detectors. [MD Tarn et al., Chem. Eur. J., 2018, 24, 13749.]