Development of a Standard Reference Thermoelectric Module: Enhancing Durability and Reproducibility through Metallic Materials and Geometric Thermoelectric Leg Shapes

Reliable standard modules are critical to ensure reproducibility and comparability in thermoelectric measurements across research laboratories. In this study, the development of a standard reference thermoelectric module (SRTEM) is presented to address this unmet need by providing a reproducible calibration platform for cross-laboratory thermoelectric measurement standardization. The SRTEM comprises eight p-n thermocouple pairs formed from metallic alloys─p-type Ni90Cr10 (Chromel) and n-type Cu55Ni45 (Constantan) or Ni95Al2Mn2Si1 (Alumel)─selected for their mechanical durability and bonding compatibility. To increase thermal resistance and ensure the consistent voltage output, a "hollow hourglass"-shaped leg geometry was adopted, reducing the effective leg cross-section while maintaining structural integrity. This design yielded an open-circuit voltage (Voc) of 89 mV, achieving a 32.8% improvement over conventional rectangular-leg modules under identical thermal gradients. Direct metal-to-metal bonding without metallization layers resulted in stable electrical contact with low contact resistance. Furthermore, the SRTEM maintained consistent performance over 300 thermal cycles (∼210 h), with no observable degradation in Voc or key output metrics. These results establish the SRTEM as a scientifically validated and practically deployable reference standard, paving the way for standardized, highly reliable thermoelectric evaluations in both academic and industrial settings.