A low-cost home-built humidity chamber for collagen films

Abstract Understanding moisture sorption and desorption behavior is essential in biomaterial development, with relative humidity (RH) being a key factor influencing a biomaterial’s moisture equilibrium profile. While commercial RH chambers are often expensive, a low-cost RH chamber was designed and constructed to facilitate the study of biomaterial behavior under defined humidity conditions. Humidification is achieved using an ultrasonic mist maker placed inside the chamber, while dehumidification is carried out with a silica gel-filled moisture trap. Fans were installed to enhance airflow and accelerate the stabilization of relative humidity values throughout the chamber. The structure is built from transparent acrylic to allow unobstructed visual monitoring of samples. Glove ports were mounted to enable in-chamber sample manipulation and preparation. Wire connection ports provide access for connecting internal electrical devices to an external control system and power supply. The control system operates via a custom-written Arduino-based program. An LCD interface displays both the current RH and temperature readings, as well as user-defined setpoints. The RH sensor was calibrated using five different saturated salt solutions to ensure accurate RH measurements. Functional tests were performed to evaluate RH stabilization, confirming reliable control across a range of 15–95 % RH. The chamber in this particular study was developed to specifically investigate the moisture sorption behavior of collagen films. With its modular design and wide humidity control range, it holds strong potential for broader application in studying and developing various moisture-sensitive biomaterials.