Mull: Low-Cost, Multi-Purpose Sensors

June 3, 2012 - 07:27 -- Sam Wilkinson
Summary: 

Mull is a series of low-cost sensor modules which communicate (and recieve power) through the headphone jack of a device, primarily smartphones. All Mull sensors consist of the same, arduino based architecture, which allow new sensor modules to be easily created using the publically available base schematic, which can be modified to add any sensor that can be connected to an Arduino. Mull sensors have two primary functions: 

 

To Educate

 

By creating a easy to read, user friendly smartphone application which displays the data recieved from a Mull module, children are free to explore their environment through a whole different perspective, like looking through a portal. Using the sensors, they can explore natural phenomena independently. This helps to create an understanding of a topic. Their low cost (£10-15) will make it easy to introduce Mull sensors not only in classrooms, but out of them to, again encouraging independent discovery. 

 

The low cost of the Mull modules does not come at the cost of accuracy and precision. All official Mull sensor modules use sensors with very high precision and accuracy, and modules such as Carbon Monoxide and Humidity use medical grade sensors. This allows older students to use Mull sensors for genuine scientific investigation and exterimentation.  The Non-Contact Thermometer module is an example of a module with a wide range of scientific applications such as measuring enthalpy change of reaction or many engineering applications.

 

To Inform 

 

Services such as Taarifa (http://taarifa.org/) help to enable citizens to communicate with their local government to report on issues in their area. There has been close collaboration to integrate data from Mull sensor modules into Taarifa reports, enabling citizens to add another layer of depth to their report, and allowing governments to see where the most serious issues lie (for example eccessive Carbon Monoxide concentration) and respond quickly. There is also work being done on creating a low-cost data logger (i.e. not a smartphone), compatible with Mull modules to allow off-the-shelf, cost-effective long term monitoring of envionmental metrics in a certain area.

Why we are working on this problem: 

The current implementation of sensors in education is mostly horrible! The devices are so expensive they can only be used by staff, disconnecting students from the subject matter. They are also very rarely used, due to their cost and no student engagement because they are so boring!!! (Can you sense the existenceof previous experience???)

What we accomplished during the event: 

During the event, we created the basic architecture of the Mull sensors, creating a prototype which could communicate over a headphone jack. We then created the schematics for the first six Mull sensors: Pressure And Temperature, Humidity, Carbon Monoxide, Air Quality, Soil Moisture, Non-Contact Thermometer. We then wrote the code for the arduino chip to read the data from the different sensors and transmit them to the phone, indicating to the phone which sensor was used. The architecture we created is an integrated, one microcontroller and one sensor per board system. Finally we made a PCB layout for one of the sensor modules (Air Quality) and worked on sending data from a Mull sensor to Taarifa in a report. We managed to get data from the arduino to Pachube, which was then used by Taarifa to make a report, and other data visualisation stuff!!!

Next steps: 

We know what the function of the phone applications need to be, we just didn't have the resourced, knowhow or time to make it. This would be the first order of buisness, making the smartphone applications. The power circuitry is untested but should work. Work would need to be done on this. Final prototypes of the sensor modules could then be made, and then after testing, PCBs manufactured. Then who knows?

Community help: 

Design and make your own sensor modules! Improve the code! Write the apps for us!!!

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