Wireless wearable wristband for continuous sweat pH monitoring Martínez Olmos, Antonio Carvajal Rodríguez, Miguel Ángel Ortega Muñoz, Mariano Orbe Payá, Ignacio De Hernández Mateo, Fernando Santoyo González, Francisco Capitán Vallvey, Luis Fermín Palma López, Alberto José Erenas Rodríguez, Miguel María Escobedo Araque, Pablo Ramos Lorente, Celia Esperanza pH sensor Sweat analysis Microfluidic cloth analytical device (μCAD) Wearable system Wireless monitoring Smartphone Several studies have shown that the determination of pH in sweat, which is one of the most accessible body fluids, can be an indicator of health and wellness, and even be used for potential disease diagnosis. On that basis, we present herein a wearable wristband for continuous and wireless monitoring of sweat pH with potential applications in the field of personal health assessment. The developed wristband consists of two main parts: a microfluidic cloth analytical device (μCAD) to collect continuously the sweat from skin with a color-based pH sensing area; and a readout and processing module with a digital color sensor to obtain the pH of sweat from the color changes in the μCAD. In addition, the readout module includes a low-power Bluetooth interface to transmit the measurements in real-time to a custom-designed smartphone application. To allow continuous operation, an absorbent pad was included in the design to retire and store thsweat from the sensing area through a passive pump path. It was found that the Hue parameter (H) in the HSV color space can be related to the sweat pH and fitted to a Boltzmann equation (R2 = 0.997). The range of use of the wristband device goes from 6 to 8, which includes the pH range of sweat, with a precision at different pH values from 3.6 to 6.0 %. Considering the typical human sweat rate, the absorbent pad allows continuous operation up to more than 1000 min. 2025-01-15T07:33:17Z 2025-01-15T07:33:17Z 2021-01-15 journal article https://hdl.handle.net/10481/99162 10.1016/j.snb.2020.128948 eng open access