Finite element modelling of the resistive heating of disposable molecular diagnostics devices

Abstract

We present a finite element model for the simulation of the resistive heating of microchannels in disposable molecular diagnostics devices by means of various resistive heating elements, and demonstrate the validity of this model through experiments. Polyimide etched foil heaters and heaters based on positive temperature coefficient (PTC) ceramics could be simple, cost-efficient and robust means of heating disposable Lab-on-a-Chip devices that depend on maintaining a given temperature range in the channels for an extended time (i.e. 15-60 minutes) with a precision of ±1-5°C. However, the design of these devices is a slow and costly process due to the many design factors involved. We demonstrate a finite element model that could reduce design time and save on prototyping costs. The validity of the model is demonstrated through various PMMA test structures designed to emulate a Lab-on-a-Chip device capable of supporting isothermal nucleic acid amplification reactions. With our experimental setups we were able to produce and maintain target temperatures for over 45 minutes with a precision of at most ±1°C deviation from the set point in a battery-operated test system without the use of a thermostat. The physical parameters of the available resistive heating elements were used in our finite element model, and the results of the simulations compared to experimental data.

Finite Element Modelling for the Optimization of Microheating in Disposable Molecular Diagnostics

“…Manufacturer specifications state the resistance of the heating element as 70.2Ω, however, in a previous work we measured initial resistance to be 76.38 ± 0.37Ω [3].…”

“…Earlier we demonstrated finite element models for passively regulated (self-regulating) and non-regulated resistive heating for temperature control in disposable Point-of-Care rapid tests using commercially available resistive heating elements [3]. In this paper, we propose a finite element model for active temperature control of disposable molecular diagnostics devices, as well as demonstrate a mini-thermostat application based on open-source (Arduinocompatible) hardware for various isothermal nucleic acid amplification assays.…”

Development of Temperature Control Solutions for Non-Instrumented Nucleic Acid Amplification Tests (NINAAT)

“…The resistance of the etched foil heating element was considered constant in the temperature range studied, and was measured at 76.38 ± 0.37 Ω [ 20 ], rather than the 70.2 Ω [ 33 ] disclosed by the manufacturer.…”

“…In previous works, we investigated finite element modelling as a tool for the thermal analysis of various commercially available heating elements [ 20 , 21 , 22 ]. In this work, we demonstrate the process by which commercially available resistive heating elements can be evaluated for use as temperature control solutions for NINAAT systems.…”

Thermal Analysis of a Disposable, Instrument-Free DNA Amplification Lab-on-a-Chip Platform

“…In previous works, we demonstrated the methodology for simulated and experimental thermal analysis of LoC NAAT systems with integrated temperature control based on commercially available electrical heating elements [ 30 , 31 , 32 , 33 ]. We compared the performance of a commercially available self-regulating heating element to a thermostat-regulated etched foil heating element in LoC NAAT prototypes and concluded that self-regulating heating was the favorable option for disposable instrument-free LoC NAAT devices [ 33 ].…”