The device was fully developed in-house, right from the conception stage to pcb fabrication and testing. it entailed the use of commonly available microcontrollers (primarily with the objective of keeping costs low to aid product penetration), bluetooth hc-05 with inbuilt antenna, switching transistors, power supply units and a relay (a single pole double throw relay was used in the test device. an opto-isolator can be implemented for faster response times) the user is supplied with an application built for android phones (future builds for ios and windows phone in the works), wherein the user can key in the user-defined password. this password can be changed periodically as per the user’s convenience. the user can also share the password with trusted relatives/friends to help the authorized relative/friend access the door. the entered password is sent via bluetooth as serial data to the on-board hc-05 which passes on the data to the arduino microcontroller. this serial data is tallied with the on-board copy of the user defined password. when the tallies do not match, the access denied message is displayed on the user’s mobile application while a tally would mean the coded microcontroller will work towards activating the switching transistor. a change in the state of the switching transistor in turn moves the spdt switch from normally closed to normally open position. this leads to a break in the circuit on the lock side (relieving the magnetized lock from the current supply), thereby opening the door for user access. the module has been tested on electromagnetic door locks and has performed exceptionally well. the range has been ascertained to be roughly 100 ft with no obstructing walls with a commensurate reduction as obstructions in the path of the device and the user’s phone increases. stress tests and a bundled application for iphone users is currently underway. another aspect that is being studied is the feasibility of implementing the module with various other data communication techniques, such as over that of wifi, over regular gsm text messages and also over nfc (near field communication). however, as per the product costs, these methods and a combination of them may or may not be implemented to maintain product appeal to the masses