Optical classification of algae species with a glass lab-on-a-chip

Abstract

The identification of submillimetre phytoplankton is important for monitoring environmental and climate changes, as well as evaluating water for health reasons. Current standard methods for phytoplankton species identification require sample collection and ex situ analysis, an expensive procedure which prevents the rapid identification of phytoplankton outbreaks. To address this, we use a glass-based microchip with a microchannel and waveguide included on a monolithic substrate, and demonstrate its use for identifying phytoplankton species. The microchannel and the specimens inside it are illuminated by laser light from the curved waveguide as algae-laden water is passed through the channel. The intensity distribution of the light collected from the biochip is monitored with an external photodetector. Here, we demonstrate that the characteristics of the photodiode signal from this simple and robust system can provide significant and useful information as to the contents of the channel. Specifically, we show first that the signals are correlated to the size of algae cells. Using a pattern-matching neural network, we demonstrate the successful classification of five algae species with an average 78% positive identification rate. Furthermore, as a proof-of-concept for field-operation, we show that the chip can be used to distinguish between detritus in field-collected water and the toxin-producing cyanobacterium Cyanothece.

In-channel integration of designable microoptical devices using flat scaffold-supported femtosecond-laser microfabrication for coupling-free optofluidic cell counting

“…[21][22][23] The surface smoothness of the microchannels was improved by smaller-pitch line-to-line scanning and optimized postthermal annealing. To enhance their functionalities, some 1D to 3D glass microcomponents, including waveguides, [24][25][26] microrotators, 27 micromirrors, 23 and microlenses, 28 have been integrated into the channels. However, the FLAE method suffers from low fabrication precision, on the order of 10 mm, determined by the wet etching process.…”

A Monolithic Micro-Tensile Tester for Investigating Silicon Dioxide Polymorph Micromechanics, Fabricated and Operated Using a Femtosecond Laser

“…Micro-tensile testers are designed for specific kind of materials. To date, despite the importance of silica glass in various technological fields such as optics, electronics and chemistry [23][24][25][26], such a tool is missing for investigating the micromechanical behavior of these materials.…”

Microalgae: Current Research and Applications

“…Images of the individual algae were also captured by a video camera implemented on the device. The acquired wave-functions identified up to five separate classes of algae in a spiked sample with an accuracy of 78% (Schaap et al, 2012b). Environmental samples would be harder to discern on this system due to detritus present and dilutions needed until only one cell was present in the detection zone at any one time.…”