Bluetooth Enabled Miniaturized Temperature Controller Device for Electrochemical Sensing Applications
Authors: Kulkarni Madhusudan , Goel Sanket 
Published: December 2020

Undeniably, Nanoparticles are of prodigious significance because of their tremendous applications in diverse fields. The structure and throughput of nanomaterials are profoundly reliant on the process utilized for their synthesis due to their unique physical and chemical properties. Synthesizing of the nanomaterials process plays a vital role in shaping the structures of nanoparticles effectively and efficiently for better yield, further these nanoparticles can be used for electrochemical sensing applications. The existing conventional technique requires very expensive and massive thermal instruments, a huge volume of reagents, a customized vessel like autoclave, stainless steel container, entails huge time with tedious and laborious approaches. In this process, the thermal management systems are considered to be an important and indispensable platform in several biological and biochemical applications. The miniaturized temperature controller device extends its usage with cost-effectiveness, rapidity, and portability. To make use of a thermal management device in micro-scale applications, it is very imperative to have an easy-to-use, effective and efficient design in the thermal management technique. This paper focuses on developing a miniaturized temperature controller system with key aspects such as cost-effective, precise, easy-to-operate, stability, automation, and compact device that can be used for electrochemical sensing applications. Such a platform is amenable to be used for biomedical or biochemical applications such as nanoparticle synthesis, DNA amplification using polymerase chain reaction (PCR) technique and rheological applications, etc. The portable device was incorporated with the arduino controller board which comes using a proportional-derivative-integral (PID) controlling approach. A PID controller is integrated with a response loop that includes an open-source library available in arduino IDE that offers a decent outcome performance constancy perceived through fine-tuning of KP=150, KI=1, and KD=70 as per the prerequisite with low tolerance. Further, a customized cartridge heater was calibrated to achieve a peak temperature of 300°C in 30 minutes, managed by a self-designed driver switching circuit and a k-type thermocouple sensor. The MAX6675 is a breakout module used with the k-type thermocouple, responsible to minimize the error, signal variation, and noise of the sensing parameters. The characterization of a cartridge heater was carried out using a feedback loop sensor. The setpoint temperature of the proposed device was around 75°C. The device showcased a temperature sensitivity of +/-2°C. Herein, an inexpensive, easy-to-operate automated and integrated device is being designed and developed for universal biological and biochemical applications. It includes a 32-bit arduino based microcontroller with 4 MB of memory and it operates in 3 – 5V range. Pro-mini usually works on 5V/16MHz and exhibits a maximum output current of 150 mA. Arduino pro mini is responsible for controlling, coordinating, and monitoring the inputs (k-type temperature sensor) and outputs (cartridge heater) respectively. The proposed device is IoT (ESP 8266-01) and Bluetooth (HC-05) enabled, with features like geotagging of data and cloud computing are the advantages of the device, wherein ThingSpeak platform allows user to analyze, access, store, and visualize live data streaming facilities. The device has been unified with additional features like real-time data accessing with a smartphone-enabled Bluetooth app storage facility. The complete device was powered up with plug-and-play by the 12V/3A adapter and dimension comes with 10.4cm*7cm*3.8cm respectively. As a proof-of-concept, the proposed thermal management device was utilized for synthesizing manganese oxide (MnO2) Nanoparticle, and the reaction sample were heated to 75°C for 8 hours, a 5 ml of beaker was used as a container for storing the reaction sample for the synthesis of nanoparticles. Further obtained MnO2 nanoflakes were subjected to characterization methods such as FESEM and EDX to examine and review the superficial morphology. A unique nanoflakes structure of MnO2 were successfully produced by the proposed temperature controller device. The obtained mean size of MnO2 nanoflakes is 22 nm. Further, the acquired MnO2 Nanoparticles can be utilized for biological and electrochemical sensing applications such as for various neurotransmitters like dopamine, histamine, and acetylcholine. Overall, the miniaturized thermal device can be used for performing diverse thermal-based reactions on a micro-scale as environment-friendly technology, with a microfluidic environment for point-of-care (POC) applications.

Index Terms- Arduino pro mini, Nanoparticles (NPs), Proportional-Derivative-Integral (PID), Manganese oxide (MnO2), Field Emission Scanning Electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Electrochemical

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