Wireless wearable wristband for continuous sweat pH monitoring

Abstract

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 the sweat 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 (R 2 =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 minutes.

Communication Requirements in 5G-Enabled Healthcare Applications: Review and Considerations

“…sleep trackers [90]; fertility and pregnancy trackers [91]; and monitors for respiration [92], blood pressure [93][94][95][96], pH [97,98], stress [99], mood [100], and sleep [101].…”

“…Examples include smart watches [ 83 , 84 ] that can monitor heart rate, blood glucose level, blood pressure, and breathing rate. Other fitness and health improvement wearables include temperature sensors [ 85 , 86 ]; pulse oximeter SpO [ 87 , 88 , 89 ]; sleep trackers [ 90 ]; fertility and pregnancy trackers [ 91 ]; and monitors for respiration [ 92 ], blood pressure [ 93 , 94 , 95 , 96 ], pH [ 97 , 98 ], stress [ 99 ], mood [ 100 ], and sleep [ 101 ].…”

A Comprehensive Review of the Recent Developments in Wearable Sweat-Sensing Devices

“…It largely uses body fluid samples such as sweat for the point-of-care diagnosis of diseases and certain laboratory tests. A microfluidic device can be sorted into the mechanism of active micropumps [ 127 , 128 ] and passive micropumps [ 129 , 130 , 131 , 132 , 133 ]. An active micropump requires an external power source to guide a continuous fluid flow with an adjustable flow rate into a microchannel.…”

Smart Materials Enabled with Artificial Intelligence for Healthcare Wearables

“…[139] Colorimetric sensors can be fabricated on different wearable substrates, such as paper, [140] hydrogel, [141] fiber, [142] fabric, [143] and yarn. [133,134] Wearable colorimetric devices include onskin platform, [135,144,145] smart band, [143] wristband, [146] contact lenses, [138] T-shirt, [133] etc., and are usually used to detect human sweat, [136,137,143] tears, [138] VOCs, [134] UV, [147] etc. Kim et al [134] demonstrated an eye-readable and wearable H 2 S sensing platform based on colorimetric dye-loaded nanofiber yarn, which could be incorporated into a worker's garment as a visual indicator; and was adequate for inexpensive mass-production (Figure 7A).…”

“…To enrich the scope of applications, colorimetric detection can be combined with other detection mechanisms or technologies into smart wearable devices. [136,[144][145][146]148] Xu et al [148] reported a resistive and colorimetric dual-mode device, in which the reduced graphene oxide (rGO)/PDMS worked as a highly sensitive semi-conductor and the colloidal crystal films worked as colorimetric substance to detect the subtle and large human motions, respectively (Figure 7E). Combining a thermal sensing module for sweat monitoring with a BLE module for wireless data transmission, Kwon et al [144] fabricated a wireless platform for the real-time analysis of sweat rate and skin temperature (Figure 7F).…”