Compact thermal sensor modules, which in some implementations can be manufactured in wafer-level fabrication processes, include features composed of or coated with a low-emissivity material to reduce or prevent detection by a sensor of radiation emitted by other parts of the module. For example, spacers that separate an optics substrate and a sensor package from one another can be composed of or coated with such a low emissivity material. In some cases, the low emissivity material has an emissivity of no more than 0.1.