Devices for fast easy monitoring of analyte levels, disease, or other physiological changes are provided. In some cases, the devices may include particles or the like that can be placed and read at the site of detection, typically on or in the skin or mucosa. In one embodiment, the particles may include anisotropic particles. Typically the devices will typically provide a visual colorimetic signal, but other signals are possible, such as smell, taste (e.g., release of food acceptable flavor), or tactile (e.g., shape change). The devices are preferably single use, disposable devices, although some may be able to provide multiple readings over a period of time. These devices may be used with any patient and are particularly useful for pediatric and elderly patients, as well as for the military, and people without health insurance. The devices can be used to assess when intervention may be required without expensive testing at a physician's office, or simply for routine maintenance of those who are concerned about their health.