The HS-20 is a bulk-resistance type relative humidity sensor that provides variable impedance output in response to adsorbed water within its proprietary thin-film polymer. The sensor operates by applying low voltage alternating current (AC 1V, 50Hz to 1kHz) across interdigitated electrodes, where the polymer's chemical functional groups dissociate into ionic groups in the presence of water, increasing electrical conductivity. It features a nominal impedance value of 67.3 kO at 25°C and 50% RH, with an inverse exponential humidity response curve across the 30% to 90% RH operating range and 0°C to 50°C temperature range. The HS-20 exhibits exceptional linearity, low hysteresis, fast response time, and excellent interchangeability, making it ideal for HVAC controls, medical devices, data loggers, automotive climate control, and environmental monitoring applications.