A multispectral-sensor-based colorimetric reader for biological assays.

Tests that depend on changes in color are commonly used in biosensing. Here, we report on a colorimetric reader for such applications. The device is simple to construct and operate, making it ideal for research laboratories with limited resources or skilled personnel. It consists of a commercial multispectral sensor interfaced with a Raspberry Pi and a touchscreen. Unlike camera-based readers, this instrument requires no calibration of wavelengths by the user or extensive image processing to obtain results. We demonstrate its potential for colorimetric biosensing by applying it to the birefringent enzyme-linked immunosorbent assay. It was able to prevent certain false positives that the assay is susceptible to and lowered its limit of detection for glucose by an order of magnitude.

Micro-Raman spectroscopy as an enabling tool for long-term intracellular studies of nanomaterials at nanomolar concentration levels.

Given the importance of nanomaterials for medicine, health and biological sciences, a method for reliable intra-cellular tracking of nanocarbon materials at ultra-low concentrations was investigated. Namely, hyperspectral imaging of DNA-functionalized single-walled carbon nanotubes inside neural stem cells was demonstrated, over several mitosis cycles, also in a 3D z-stacking mode.

Compact inline optical electron polarimeter.

A compact optical electron polarimeter using a helium target is described. It offers a maximum fluorescence detection efficiency of ~20 Hz/nA, which is an order of magnitude higher than that of earlier designs. With an argon target, this device is expected to have a polarimetric figure-of-merit of 270 Hz/nA. By relying on a magnetic field to guide a longitudinally spin-polarized electron beam, the present instrument employs fewer electrodes. It also uses a commercially available integrated photon counting module. These features allow it to occupy a smaller volume and make it easier to operate.