This is an overview of the SensorPush Bluetooth Hygrometers. I had recently purchased a number of these to help in the curing process.
A word of warning, these are a bit pricey as far as miniature hygrometers go. But, these seems to work very well with features that may be useful to you.
Now, the hygrometer:
Backside, note the hole for the humidity sensing component:
The cover is removable for battery replacement (and possibly for cleaning anything that gets into the hole). These sensors are not waterproof.
The size of the sensor itself is approximately 1.5 x 1.5 x 0.5 inches. Here is what one looks like in a small 12 ounce mason jar:
Clearly, there is no display to actually tell what is going on with the humidity and temperature.
Instead, there are a couple of ways to retrieve and store the data.
The first way requires a bluetooth capable IOS or Android device to be able to query the device. The hygrometer itself is capable of storing something like 20 days of data. As soon as your device is in range of the sensor(s), the data is downloaded to the sensor push application.
The second method is through the use of a bluetooth gateway that can be purchased from SensorPush. In this case, any hygrometer that is within range of the gateway will automatically push data to cloud based storage. This will allow wifi or ethernet connected device, again Android or IOS based, to query the data from anywhere in the world. Pretty nifty if you don't mind storing the data in the cloud.
Here is what the gateway looks like:
The gateway will connect to your wifi or ethernet based network.
You can purchase any number of these hygrometers and add them to the SensorPush application almost seamlessly. All you need to do is to place the "new" sensor near the Android or IOS device with bluetooth.
The application will automatically detect the new sensor and add it to your dashboard. The same method is used to add a gateway if you go that route. Here is what the dashboard looks like with several paired sensors:
You are also able to set-up ranges of temperature and humidity that are acceptable, values outside of the set range will generate an alert:
And, the dashboard with the ranges set for the first sensor:
You can drill down into the data for each individual sensor to view graphs of the stored data by hour, week, day, month, or years. For instance, here is the view for the weekly data from one of the sensors:
And, scrolling down, you can see the temperature distribution, humidity distribution, and other metrics (such as the battery temperature being 1.17 trillon degrees, opps):
You'll also note that there is an export data button. For the data hounds, it's easy enough to export the data by date range. For plotting in Excel, for instance.
Here is the exported data from a sensor located in a curing jar (imported into Excel):
And, another one as I try to get the humidity under control:
The overall accuracy as specified by the SensorPush folk is
temperature: ±0.3°C / ±0.5°F typical ±0.5°C / ±0.9°F maximum
humidity (20-80%): ±3% typical ±4.5% maximum
humidity (0-1005): ±4.5% typical ±7.5% maximum
The relative humidity is capable of being calibrated using accepted methods for humidity calibration including the use of Boveda salt based calibration packs.
They also claim a 1-2 year life expectancy with the pre-installed battery (replaceable).