Behraad Bahreyni: revolutionizing microsystems

A team of researchers at Simon Fraser University’s School of Mechatronic Systems Engineering, led by Professor Behraad Bahreyni, is leading a big revolution in the tiny world of microsystems.

The Integrated Multi-Transducer Systems Laboratory (IMuTS) team investigates how miniaturized devices and structures – known as microsystems – can improve functionality, performance and safety in a number of applications including security, robotics and smart devices.

Films for sensitive infrared sensors that will be used to build directional pixels for 3D image sensors.

Taking sensors in a new direction

Light sensors

By applying microsystem technologies to sensors, the IMuTS team is developing a suite of ultrasensitive sensors to measure diverse phenomena including light direction, acceleration waves, ambient gas concentrations, and angular rate, along with micromechanical oscillators for telecommunications.

Among the group’s inventions is a first-of-its-kind vector light sensor that – unlike typical sensors – tracks light source as well as light intensity. Using triangulation, two sensors can then estimate distance to a light source. This has important applications, says Bahreyni, because humans and other warm-blooded animals radiate infrared light.

So, by fine-tuning the sensors to respond to infrared, it is possible to track humans for improved safety – for example, in factories where humans and heavy machinery co-operate – or for use in consumer electronics such as mobile devices.

Placed in an array, the sensors can take images to a whole new dimension, capturing both depth perception and a light intensity map. A 3D image, in other words. This is groundbreaking, explains Bahreyni, because two cameras are normally required to create 3D images; each lens capturing the subject from a slightly different perspective to create a sense of depth.

“The sensor array is less than a millimeter in thickness, but will be able to focus onto any object in the field without using optical lenses,” says Bahreyni.

“It’s all about taking signal processing from an optical domain to a digital domain." The new sensors could find use in tiny lens-free cameras that could be embedded in all kinds of things, from wearable consumer gadgets to security systems.

Sound sensors

In addition, Bahreyni’s team is developing microsensors to detect sound direction. Current systems use large arrays of microphones to map variations of sound to derive sound direction. The IMuTS lab instead is developing devices to measure sound pressure and direction simultaneously with ultrasensitive accelerometers.

The accelerometers under development at the IMuTS lab are approximately 1000 times more sensitive than micro-accelerometers currently used for crash detection in vehicle airbag deployment systems, and orientation detection in mobile devices. As a result, they can detect movements as small as 1pm (that is 1/100^th of a hydrogen atom diameter) across the audio band. The research will provide novel solutions for many applications ranging from geophysical studies to border security.

The IMuTs lab's ultra-sensitive accelerometers can detect sound waves.

Powering the future

Bahreyni envisions the next major technological breakthrough to be the advent of ubiquitous intelligent systems connected to a wider network. Known as the Internet of Things, “These intelligent systems are composed of miniaturized sensors that capture relevant information, locally process the collected data, and transmit the information to other sensory nodes or central processing systems,” says Bahreyni.

“We are on the verge of a new era in human history where nearly all components around us will be smart in the sense that they monitor, process and react to changes in their environment.”

The Internet of Things has enormous potential, but faces a key challenge that Bahreyni’s team hopes to help overcome: if information is to be distributed wirelessly, sensors must function using very little energy.

“Batteries have a limited life as an energy source and although solar cells can be effective, they require light to function.” Says Bahreyni.

“More diverse energy sources are needed. Regardless of the energy source, energy consumption must be reduced to perform the desired function more often and for a longer period of time.”

The solution, then, lies in miniaturization: “Whether electronic or mechanical, small devices need little power to operate,” explains Bahreyni. When properly designed, micromechanical and microelectronic systems can conduct a variety of sensing and data acquisition functions consuming only microwatts; thousands of times less than the power needed for a cellular phone in standby.

To achieve this, Bahreyni is leading research on a revolutionary method of employing microelectronic devices, such as diodes and transistors, into the structure of the micro- and nano-mechanical devices.

“We are using properties of microelectronic devices that people knew existed, but that had never been employed with a micro-mechanical system,” says Bahreyni.

“We have just cracked open the door to an area of research with the potential to revolutionize the field and there is much to be learnt. Thanks to the leading-edge facilities such as 4D Labs and IMuTS Lab, SFU is very well positioned to lead the research in this field.”

PhD students Shirin Edalatfar (left) and Amin Rasouli test microresonators fabricated at SFU.

About the IMuTS Lab

IMuTS Lab is the leading Canadian laboratory with research concentration on studying the basic physical phenomena at small scales and employing them to develop solutions and deliver applied results.

This is achieved through conducting an experimental research on the development of micro– or macro–scale solutions through the integration of micro-electro-mechanical systems (MEMS), nanomaterials, and integrated circuits (IC). IMuTS research group has access to state-of-the-art facilities for fabrication and characterization of mico- and nano-devices on SFU campus. Thanks to the progressive IP policies at SFU, much of the research at IMuTS Lab is carried in collaboration with industrial partners from automotive, defense, space, security, and telecommunication applications.

About professor Behraad Bahreyni

Behraad Bahreyni, PEng, SMIEEE, is the founder and director of the Integrated Multi-Transducer Systems Laboratory (IMuTS Lab) at Simon Fraser University. Coming to SFU from industry after a post-doctoral fellowship at Cambridge University, Bahreyni has maintained a balance of fundamental and applied research in collaboration with global industrial partners.

His research is focused on the development of sensing systems, from device design and microfabrication to packaging and signal processing. His team has developed numerous novel devices and systems that have raised the performance bar in applications ranging from ultra-sensitive inertial sensing and touchless interfaces for mobile devices to low-power electronic circuit design and chemical/biological sensing.

Professor Bahreyni examines variable capacitors for radio frequency microelectromechanical systems.