Maintaining precise isothermal conditions in portable nucleic acid amplification tests (NAATs) is critical for reproducible results but remains challenging with conventional single-sided thin-film heaters, which exhibit temperature gradients and strong dependence on ambient conditions. To close this gap, we engineered ThermiQuant(TM) VitroMini, a dual-sided heater design that achieves volumetric-level temperature uniformity using thin-film heaters while preserving optical transparency for real-time colorimetric loop-mediated isothermal amplification (LAMP) analysis on microfluidic paper-based analytical devices (PADs). The device integrates two independently regulated indium tin oxide (ITO) heaters (8 ohms each) controlled by independent proportional-integral-derivative (PID) algorithms. Heaters were evaluated under controlled ambient environments of 4 degrees C (refrigerated), 23 degrees C (room temperature), and 50 degrees C (oven). Analytical tests were performed using a colorimetric LAMP assay targeting the SARS-CoV-2 orf7ab gene on PADs preloaded with dried LAMP reagents, with time-lapse images (30 seconds interval) analyzed via Amplimetrics(TM) software. VitroMini maintained 65 +/- 0.5 degrees C across 4 to 50 degrees C ambient conditions and achieved a limit of detection of 50 copies/reaction (6.7 copies/microliter), with quantification times (Tq) linearly correlated with log10 DNA concentration. Dual-sided heating eliminated temperature bias, condensation artifacts, and ambient-dependent variability while preserving optical transparency for real-time LAMP quantification. ThermiQuant(TM) VitroMini bridges the gap between benchtop volumetric heaters and portable diagnostic devices, offering a compact, low-power, and field-deployable platform for decentralized mole