Micro-patterning and characterization of PHEMA-co-PAM-based optical chemical sensors for lab-on-a-chip applications

Abstract

We report a novel method for wafer level, high throughput optical chemical sensor patterning, with precise control of the sensor volume and capability of producing arbitrary microscale patterns. Monomeric oxygen (O2) and pH optical probes were polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form spin-coatable and further crosslinkable polymers. A micro-patterning method based on micro-fabrication techniques (photolithography, wet chemical process and reactive ion etch) was developed to miniaturize the sensor film onto glass substrates in arbitrary sizes and shapes. The sensitivity of fabricated micro-patterns was characterized under various oxygen concentrations and pH values. The process for spatially integration of two sensors (Oxygen and pH) on the same substrate surface was also developed, and preliminary fabrication and characterization results were presented. To the best of our knowledge, it is the first time that poly (2-hydroxylethyl methacrylate)-co-poly (acrylamide) (PHEMA-co-PAM)-based sensors had been patterned and integrated at the wafer level with micron scale precision control using microfabrication techniques. The developed methods can provide a feasible way to miniaturize and integrate the optical chemical sensor system and can be applied to any lab-on-a-chip system, especially the biological micro-systems requiring optical sensing of single or multiple analytes.

A platform for high-throughput bioenergy production phenotype characterization in single cells

“…Furthermore, in addition to using just the sensor emission intensity as a readout, one can utilize time-resolved measurements of sensor emission decay times to calculate changes in analyte concentration2122. Alternatively, the different sensors can be separated spatially inside the microwells using photo patterning or robotic sensor deposition, similar to the approaches utilized by our group2333. The system throughput can be further increased by implementing experimental designs for running multiple assays in parallel.…”

Microfabrication Processes and Applications of Liquid Photosensitive Materials

“…51 In addition, here the fluorescence imaging method can generally provide good visualization of the targeted materials for measurement of micropattern. 52 Hence, as illustrated in Figure 6.14, the Ormocer cylindrical pillars made of polymers contain neuroblast-like cells observed by fluorescence imaging. 53 The green cytoskeleton and blue nuclei are clearly colored in the fluorescent micrographs.…”

Integration and application of optical chemical sensors in microbioreactors

“…Spin coating can produce homogenous layers on flat surfaces over a large area with a layer thickness down to a few hundred nanometres for optical sensor polymers. 34,35 The sensor formulation is applied to a smooth surface and spun in order to spread the fluid evenly using rotational force. Grist et al 36 used this technique to create a sensor film which they then structured using laser ablation (see Fig.…”

“…Zhu et al demonstrated a sensor patterning method which used photolithography to produce sensor layers in arbitrary shapes and sizes with high precision. 35 Related to photopolymerization, Nock et al 41 demonstrated the use of photoresists for the production of a PDMS stamp for the integration of sensor layers. This method could also be referred to as micro contact-printing.…”