The invention addresses confounding difficulties involving continuous sweat analyte measurement. Specifically, the present invention provides: at least one component capable of monitoring whether a sweat sensing device is in sufficient contact with a wearer's skin to allow proper device operation; at least one component capable of monitoring whether the device is operating on a wearer's skin; at least one means of determining whether the device wearer is a target individual within a probability range; at least one component capable of generating and communicating alert messages to the device user(s) related to: wearer safety, wearer physiological condition, compliance with a requirement to wear a device, device operation; compliance with a behavior requirement, or other purposes that may be derived from sweat sensor data; and the ability to utilize aggregated sweat sensor data that may be correlated with information external to the device to enhance the predictive capabilities of the device.

The invention addresses confounding difficulties involving continuous sweat analyte measurement. Specifically, the present invention provides: at least one component capable of monitoring whether a sweat sensing device is in sufficient contact with a wearer's skin to allow proper device operation; at least one component capable of monitoring whether the device is operating on a wearer's skin; at least one means of determining whether the device wearer is a target individual within a probability range; at least one component capable of generating and communicating alert messages to the device user(s) related to: wearer safety, wearer physiological condition, compliance with a requirement to wear a device, device operation; compliance with a behavior requirement, or other purposes that may be derived from sweat sensor data; and the ability to utilize aggregated sweat sensor data that may be correlated with information external to the device to enhance the predictive capabilities of the device.

The invention addresses confounding difficulties involving continuous sweat analyte measurement. Specifically, the present invention provides: at least one component capable of monitoring whether a sweat sensing device is in sufficient contact with a wearer's skin to allow proper device operation; at least one component capable of monitoring whether the device is operating on a wearer's skin; at least one means of determining whether the device wearer is a target individual within a probability range; at least one component capable of generating and communicating alert messages to the device user(s) related to: wearer safety, wearer physiological condition, compliance with a requirement to wear a device, device operation; compliance with a behavior requirement, or other purposes that may be derived from sweat sensor data; and the ability to utilize aggregated sweat sensor data that may be correlated with information external to the device to enhance the predictive capabilities of the device.

A non-invasive epidermal electrochemical sensor device includes an adhesive membrane; a flexible or stretchable substrate disposed over the adhesive membrane; and an anodic electrode assembly disposed over the flexible or stretchable substrate including an iontophoretic electrode. The device includes a cathodic electrode assembly disposed adjacent to the anodic electrode assembly over the flexible or stretchable substrate and includes an iontophoretic electrode. Either the cathodic electrode assembly or the anodic electrode assembly also includes a sensing electrode that includes a working electrode and at least one of a counter electrode or a reference electrode. The iontophoretic electrode in either the anodic electrode assembly or the cathodic electrode assembly that includes the sensing electrode is disposed on the substrate to at least partially encompass the working electrode and the at least one of the counter electrode or the reference electrode. The device includes an electrode interface assembly including independent electrically conductive contacts.

The disclosed invention provides a biofluid collection device configured with an open microfluidic network, which facilitates nanoliter-scale biofluid collection and transport for biosensing applications. In one embodiment, a biofluid sensing device placed on the skin for measuring a characteristic of an analyte in sweat includes one or more biofluid sensors and a hexagonal open microfluidic network biofluid collector. The disclosed collector provides a volume-reduced pathway for sweat biofluid between the one or more sensors and sweat glands when the device is positioned on the skin. In another embodiment, a biofluid collector includes a network of microchannels comprising three or more repeatedly intersecting channels that provide redundant pathways for biofluid transport. Embodiments of the disclosed invention are also directed to highly stable peptide-based self-assembled monolayers (SAM) and methods of making the SAMs. In some embodiments, the peptide-based SAM is formed on a component of a biofluid sensing device.

A sensing device allows detection of biological quantities in ways that are minimally invasive. Micrometer or nanometer sized needles allow sensing of bodily fluids in a minimally invasive method. The device comprises electronics and power harvesting. Antennas or coils allow communication and power harvesting from an external device, which can be attached to smartphones to allow operation of a camera and camera light for biosensing.

A sweat sensing device includes a plurality of sweat collection pads communicating with a sensor. Each of the pads is activated by a timing circuit which allows one or more of the pads to be activated at a selected time and subsequent deactivated after a defined period of time. This allows for selective collection of sweat from a plurality of pads over a prolonged period of time. An impedance measuring circuit can be employed to determine if one or more of the pads becomes disconnected, in order to avoid irritation. Further, the devices can use a common microfluidic device which both transports sweat activating substance, such as pilocarpine, to the surface of the skin and directs sweat away from the skin to a sensing device.

The invention addresses confounding difficulties involving continuous sweat analyte measurement. Specifically, the present invention provides: at least one component capable of monitoring whether a sweat sensing device is in sufficient contact with a wearer's skin to allow proper device operation; at least one component capable of monitoring whether the device is operating on a wearer's skin; at least one means of determining whether the device wearer is a target individual within a probability range; at least one component capable of generating and communicating alert messages to the device user(s) related to: wearer safety, wearer physiological condition, compliance with a requirement to wear a device, device operation; compliance with a behavior requirement, or other purposes that may be derived from sweat sensor data; and the ability to utilize aggregated sweat sensor data that may be correlated with information external to the device to enhance the predictive capabilities of the device.

Devices that sense sweat and are capable of providing chronological assurance are described. The device uses at least one sensor to measure sweat or its components and to determine a sweat sampling rate. The chronological assurance is determined, at least in part, using the sweat sampling rate. The sweat sampling rate may be determined, at least in part, using a sweat volume and/or a sweat generation rate, both of which may be measured or predetermined.

Methods for treating fluid overload in a subject comprise shifting fluids directly and non-invasively from an interstitial compartment of the subject to skin of the subject through controlled local sweating. Methods of the invention allow for removal of excess fluid from the interstitial compartment of the subject and treat fluid overload in the subject. Sweat stimulation systems comprise a chamber and first and second relative humidity sensors. The chamber is sized to fit around a body part of a subject, comprises an inlet and an outlet, and is configured such that air flows through the chamber from the inlet to the outlet. The first relative humidity sensor is operably located inside the inlet, and the second relative humidity sensor is operably located proximate the outlet.