Abstract: Devices and methods are described herein for directly and accurately measuring sweat flow rates using miniaturized thermal flow rate sensors. The devices (100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500) include the flow rate sensors (220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1220, 1320, 1420) in or adjacent to a microfluidic component (230, 330, 430, 530, 630, 730, 830, 930, 1030, 1130, 1230, 1330, 1430, 1530) of a wearable sweat sensing device. The devices and methods optimize the sensitivity of the flow rate sensors, while minimizing the presence of noise, in order to accurately and directly measure sweat flow rates.

Abstract: Embodiments of the disclosed invention provide wearable devices that use a humidity sensor to measure sweat rate generated from an area of skin. A sensing chamber is continuously filled with a sweat sample, which forms a droplet and alters the humidity measured within the chamber. Once the sweat sample droplet expands to the edge of the chamber, the droplet contacts a wick and is drawn away, so the chamber can fill with a subsequent droplet. The device uses a droplet volume and the time required to reach a maximum humidity to calculate a sweat rate. A pump is used to draw old sweat sample out of the wick to allow extended device operation. Some embodiments also include capacitive sensors to perform back up measurements. Another set of embodiments includes alternatively shaped sensing chambers configured to reduce sample volumes or improve function. A method for determining sweat rate based on humidity sensor measurements is also included.

Abstract: Devices and methods are described herein for directly and accurately measuring sweat flow rates using miniaturized thermal flow rate sensors. The devices (100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500) include the flow rate sensors (220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1220, 1320, 1420) in or adjacent to a microfluidic component (230, 330, 430, 530, 630, 730, 830, 930, 1030, 1130, 1230, 1330, 1430, 1530) of a wearable sweat sensing device. The devices and methods optimize the sensitivity of the flow rate sensors, while minimizing the presence of noise, in order to accurately and directly measure sweat flow rates.

Abstract: A device for determining the amount or concentration of an analyte in a fluid sample and a flow rate of the fluid sample in a channel is provided. The device includes a chamber including a channel and an opening the channel in fluid communication with the opening. The device further includes a wicking component positioned adjacent to the opening configured to receive an amount of fluid from the channel. The device may further include an analyte sensor positioned on the wicking component, the analyte sensor configured to detect an analyte in fluid in contact with the analyte sensor, wherein the wicking component is configured to contact the amount of fluid with the analyte sensor. Alternatively the device may include at least one pair of electrodes configured to determine a flow rate of the fluid in the channel.