Controlled, stable and uniform temperature environment with quick response are crucial needs for many lab-on-chip (LOC) applications requiring thermal management. Laser Induced Graphene (LIG) heater is one such mechanism capable of maintaining a wide range of steady state temperature. LIG heaters are thin, flexible, and inexpensive and can be fabricated easily in different geometric configurations. In this perspective, herein, the electro-thermal performance of the LIG heater has been examined for different laser power values and scanning speeds. The experimented laser ablated patterns exhibited varying electrical conductivity corresponding to different combinations of power and speed of the laser. The conductivity of the pattern can be tailored by tuning the parameters which exhibit, a wide range of temperatures making them suitable for diverse lab-on-chip applications. A maximum temperature of 589 °C was observed for a combination of 15% laser power and 5.5% scanning speed. A LOC platform was realized by integrating the developed LIG heaters with a droplet-based microfluidic device. The performance of this LOC platform was analyzed for effective use of LIG heaters to synthesize Gold nanoparticles (GNP). Finally, the functionality of the synthesized GNPs was validated by utilizing them as catalyst in enzymatic glucose biofuel cell and in electrochemical applications.
In this work, a miniaturized platform for electrochemical detection of hydrazine, has been developed using droplet paper based three electrode system. Copper oxide cluster (CuO) immobilized on the surface of graphite sheet (Grp@CuO) is used as a working electrode. The developed Grp@CuO showed a surface-confined delayed redox response at an electrode potential (E1/2) −0.24 V vs Ag/AgCl in pH 7 phosphate buffer solution (PBS). The physicochemical characterization of the Grp@CuO revealed the electro deposition of CuO cluster on the surface of graphite sheet. Grp@CuO displayed selective electro-catalytic activity towards the detection of hydrazine in pH 7.0 PBS. A systematic linear increase in the oxidation current is observed in the range of 1 μM to 7 μM at an applied potential of −0.6 to 0.2 V vs Ag/AgCl with an excellent current sensitivity, lower detection limit (0.3482 μM). The fabricated miniaturized droplet-based sensor showed zero interference from other chemicals. Therefore, it is a viable option to be used in detection of hydrazine in real samples. Finally, the prepared platform was harnessed to real water samples for hydrazine detection.
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