Control sensors and actuators based on nodeMCU platform, chip ESP8266.
Your simple network based on nodes low cost and your Android device as Controller. Nodes are the nodeMCU development kit. They can be purchased for 5-6 dolars on alliexpres or ebay.
NodeMCU can be a temperature or humidity sensor. You can easyly build your own motion detector or servo control
NodeMCU is based on chip ESP8266. This can be programmed in Lua, C++, comandos AT and using Arduino API.
This app uses a very simple message protocol, based on UDP messages. You have to copy and upload the arduino sketch supplied with the app. Use Arduino IDE for this. Search on the web how to set Arduino IDE for a nodeMCU board.
Feel free to change and customize the arduino sketches. Futures versions will provide an auto-reset function in order to rejoint the network connetion in case of lost connection. Also more sensors an actuators will be available: heating control, consumption control (water and electricity), servo ...