SmartMat: Wi-Fi floor mat that can alert mobile devices
The SmartMat is a Wi-Fi connected sensor that goes under door mats and detects the weight of people or pets and triggers actions.
Need a door mat that sends you a text when your dog is sitting at the door wanting to come in? Need to receive a text alert when an elderly relative leaves a room or steps on the door mat to leave the house? Or how about having the TV automatically turn on when you sit down on your couch?
The SmartMat can do all this and more! The SmartMat uses a smart plastic film that is force sensitive. When coupled with the Wi-Fi enabled Electric Imp micro controller, the SmartMat connects to the Internet of Things through your home Wi-Fi signal and is able to perform many pre-programmed tasks as well as be monitored in real-time through any web browser. Additionally, the SmartMat can be custom programmed to carry out your own ideas using the browser-based programming platform used by the Electric Imp.
What is the SmartMat?
The SmartMat is a thin, durable, and flexible floor mat that triggers actions based on the weight of who or what is on the mat. Different combinations of triggers and actions can be selected using any mobile device or computer with a web browser to program the SmartMat to perform a multitude of tasks. The SmartMat can even be used to control light bulbs, appliances, and other smart home products.
Example SmartMat Scenarios:
Automatic Room Lighting
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How Does it Work?
Most large floor sensors work like an electrical switch when they are stepped on. When there is no weight on these types of sensors, they are an open circuit, and when weight is applied, two conductive layers touch, closing the electrical circuit. These types of floor sensors can have poor durability because the mechanism by which the conductive layers are separated can wear and break down with repeated use. Even if the two conductive layers barely touch (due to a crack or break in the separation layer), these traditional sensors will give the same output they give when activated, causing false triggers and a malfunctioning sensor.
With the SmartMat, there is no separation layer to wear or break down because the polymer film itself electrically changes in response to applied weight. Furthermore, the force-dependent output ensures a large degree of measurable change between no weight and the weight at which an action will be triggered (i.e. a dog's weight), giving the microprocessor ample opportunity to detect false triggers.
The force-sensitive polymer film used in the SmartMat differs from all other force sensing film technologies by the physics of how it obtains force measurements. Other force-sensing film technologies use rubber-like polymers or inks that change their electrical resistance due to compressive deformation of the material - i.e. those materials get thinner when force is applied to them. In order to provide measurements, the material must be soft enough to deform. This causes relatively poor long-term durability.
Conversely, the sensor polymer contained in the SmartMat has the highest impact and wear resistance of any thermoplastic (ultra-high molecular weight polyethylene), such that even when very high forces are applied, there is negligible compressive deformation of the polymer film. This technology relies on small changes in the nano-scale surface roughness of the polymer film when force is applied. Because these changes are at the nano-scale, they multiply by orders of magnitude for a nominal sized film sensor, causing dramatic changes in the electrical resistance that can easily be detected by the electronics.
The SmartMat consists of 5 different plastic films in a layered structure. The middle layer is the polymer sensor film and on top of and below it are conductive film layers. The outer two layers of ultra rugged polymer film serve to hold the mat together and give it durability and protection from the weather. All 5 layers of the SmartMat are heat-sealed together providing water-tight protection.
The SmartMat uses the Electric Imp platform (www.electricimp.com) which consists of a Wi-Fi enabled micro controller that collects and processes the SmartMat data, and a cloud-based server that receives the data and performs actions and other programmable features such as email or text message alerts. The Electric Imp is programmed via a browser-based IDE using a scripting language called Squirrel, making it relatively easy to program for those interested in creating their own custom features and uses for the SmartMat.
All that's needed to get the SmartMat connected to your existing wireless network is a smartphone for programming your wireless network SSID and password into the Electric Imp. Once this is done, your SmartMat will store these settings and remain connected to the Internet of Things through your home Wi-Fi network.
The SmartMat can run on battery power for a limited time or the included AC adapter can be used for longer-term or permanent placement. Depending on the application for which the SmartMat is used, the expected life of a single 9V alkaline battery varies. If the SmartMat is setup to continuously transmit data and remain connected to Wi-Fi, the expected battery life is approximately 3 days (the average current consumption of the electronics is 10mA at 3.3V). However, for many applications, such as alerting a phone when a pet is at the door ready to come in or go out, continuous data transmission is not necessary. For extended battery life, a power saving mode is available for selection in the setup software. When the power saving mode is active, the SmartMat will go to sleep after 60 seconds of not sensing any weight. In the power saving sleep mode, the current consumption of the electronics is approximately 12 µA - over 800 times less power than when actively transmitting data. When the SmartMat is asleep, any weight it senses will cause it to wake up and re-connect to Wi-Fi and resume transmission of data. The amount of time it takes for the SmartMat to re-connect varies from approximately 3 to 5 seconds depending on specific wireless network conditions.
What does all this mean for battery life? If the SmartMat has weight on it for an average of 15 minutes out of every day, with power saving mode enabled, the expected battery life of a standard 9V alkaline is over 100 days! This would be typical for a pet alerting usage scenario where the SmartMat may send 3 or 4 alerts per day, or for a home entrance monitoring application where the SmartMat might log 15 entrance/exits per day. In applications where the SmartMat might see use only once a day, the expected battery life can be even longer. For example, in an application where the SmartMat is awake (with weight applied) for only a couple minutes per day, the expected battery life is over one year!
The drawback of the power saving mode is the 3 to 5 second latency required for the SmartMat to reconnect to Wi-Fi after it senses weight. For the majority of applications, this probably doesn't matter, but for some applications, like automatically turning on room lights, this may not be desirable. Therefore, the included AC adapter can always be used.
The battery life can be checked at any time through the control software, and when the battery has less than 10% remaining, any alerts sent by the SmartMat will include a low battery notification.
Each SmartMat's Electric Imp has its own unique webpage that has been programmed to allow the user to select the type and level of the trigger and the action that will be performed when the SmartMat is triggered. Each SmartMat's webpage also allows the user to graphically monitor the current condition of the SmartMat in real-time. Thus, the SmartMat can be controlled from any computer or mobile device with a web browser, and making changes to the SmartMat's configuration is quick and easy to do from anywhere.
In the example above, the SmartMat is configured in the pet alerting mode where it sends an sms text message to a phone that has a custom 'dog bark' ring tone selected for texts received from the SmartMat. Thus, no matter where you are in the house or how loud the TV is, you will be notified when the dog is ready to come inside, before he starts scratching up the door.
Real Time Monitoring:
The video above shows the SmartMat software's graphical real-time monitoring function.
The video above shows the real-time graphing function of the software illustrating the sensitivity of the SmartMat - it has no problem detecting the weight of a cat walking on the floor mat.
Automatic Room Lights:
Have you ever walked into a dark room with your hands too full to turn on the light switch and tripped over a misplaced item that was left in the middle of the floor? In the video example above, the SmartMat along with the Wi-Fi connected power strip is used to control the room lights, turning them on when you enter and off when you leave. What a great way to save electricity and not have to fool with a pesky light switch. And unlike motion-sensor lighting controls, the lights won't turn off while you're sitting still!
The SmartMat can be placed under a couch cushion to power a device on when you sit down and off when you get up. The time delay after the SmartMat detects you have gotten up and when the device powers off can be customized using the control software.
The SmartMat can also be used to detect the weight of a package or shipment, alerting you when the shipment arrives. Furthermore, an alert can also be sent when the SmartMat detects that the package has been removed, allowing for tamper or theft monitoring.
Use the SmartMat to astonish and astound unsuspecting subjects!
Risks and challenges
Working circuit boards and functional software have already been created as shown in the videos and pictures. The webpage user interface to select the type of trigger and the action to occur will continue to improve during the campaign and up until the first batch of SmartMats are ready to ship.
As with any project that has rewards that must be assembled, there is a risk of delays arising from shortages of materials. To mitigate this risk, many steps have already been taken. A large quantity of the force-sensitive polymer film layer of the SmartMat has already been obtained and more can be quickly sourced if necessary. Multiple vendors have been identified to supply the conductive film electrode layers and outer protective layers, so if any delays are experienced with the primary vendor, the material can be sourced from a secondary vendor.
For the electronic components, multiple vendors have already confirmed more than enough quantity to fulfill the requirements of this project. Additionally, the circuit board has already been designed with all components tested. As soon as the project has ended, the circuit boards and all of the components will be ordered.
Many valuable lessons were learned from the Sensor Film Kit kickstarter project (http://kck.st/17CmGuK), which successfully shipped all rewards on time. Those lessons will be applied to making the SmartMat project even more successful.Learn about accountability on Kickstarter
- (29 days)