Sensors are key to making interactive systems that gather, analyze, and put to use massive amounts of data about the world around us. The Internet of Things (IoT) and wearable devices wouldn't be nearly as enticing without the capabilities made possible by sensors, as our devices, cars, homes, and more are getting smarter and improving our daily lives thanks to the wealth of information they're able to gather. DIY projects are also becoming more advanced and sophisticated thanks to the availability of low-cost, high-quality sensors, as well as communities that can help makers put them to use.

"There are so many great sensors coming out," says Limor "Ladyada" Fried, Founder and Engineer at Adafruit (www.adafruit.com), an open-source DIY tools, equipment, and electronics company. "A single-axis accelerometer used to be $40. Now you can get a full 9-degrees-of-freedom sensor for $5! Incredible how the demand for sensor-enabled cell phones and wearables has increased what's available."

Though inexpensive and widely available with limitless project possibilities, working with sensors in a DIY project can be challenging and time consuming. Fried, who has been named Entrepreneur of the Year by Entrepreneur magazine and made many "innovator" and "influencer" lists, cites considerations such as figuring out if a sensor is analog, ratiometric, absolute, or digital I2C output, and if the sensor requires repeated start. But instead of taking the time to figure out all the details alone, Fried and the Adafruit team have a system down to help alleviate the difficulties of working with a new sensor.

"Every sensor has its own little quirks," Fried says. "One of the things we do for every sensor in our shop is go through and make an Arduino library with a demo. That way you can get it wired and read valid data as soon as possible. Having a known-good platform is key, and an Arduino is only $30 – it's like a universal eval board."

Adafruit offers nearly 200 sensor parts among a variety of sensor types that are compatible with multiple platforms. In addition to selecting, testing, and designing products of her own, Fried also contributes to the Adafruit Learning System, which contains tutorials on integrating sensors into DIY projects and other maker tips in a Pinterest-style format (learn.adafruit.com). Dozens of sensor tutorials range from teaching makers the basics of different sensor types, to more advanced lessons on creating garden monitoring systems, spatial navigation systems, GPS-enabled pet collars, and biometric lockboxes with a variety of sensor components.

Where sensors meet accessories

Out of all the sensor products and tutorials available, Fried says those related to wearables are the most popular.

"We have hundreds of tutorials on using sensors, but our most popular ones by far are the wearable ones," Fried says. "The best place to see the cool future of DIY sensors is wearable electronics."

The possibilities of wearables go way beyond the traditional smartwatches and fitness bands that have recently exploded in popularity. The Adafruit team, for example, used a TAOS TCS34725 RGB color sensor with an IR filter that detects light bouncing off an object to make color-changing accessories (Figure 1). Another example would be a wearable accessory with a UV sensor that detects when it's time to put on a hat. In addition, Adafruit has a whole #WearableWednesday blog and video series and its own FLORA and GEMMA DIY wearable platforms.

A better feel on future sensors

Though sensors have come a long way, there are still opportunities to bring certain capabilities down in scale and increase their availability to the general public. For example, Fried sees gesture-sensing capabilities like those of the Xbox Kinect as an area that could use more work.

"A low-power Kinect-type sensor, something you could power off of 3 V and small enough to embed into anything would be so great," Fried says. "People love the idea of gesture and location-mapping sensing."

With how far sensors have progressed in the last decade, it's exciting to think of what new sensing capabilities will become widely available next for makers.