For much of the 20th century, automobiles were engineered based on mechanical performance, drivability, and analog systems. Automotive safety and precision design were largely reactive, founded on after-the-fact modifications instead of in-board intelligence. As automobile technology evolved, there was an added level of sophistication — not only in electronics and the drivetrain, but also in sensing. The shift from mechanical to sensor feedback was a significant development. It was this evolution that enabled many of the smart systems in modern vehicles, ranging from adaptive braking to collision sensing.
One such shift started with the intersection of microelectromechanical systems (MEMS) and complementary metal-oxide-semiconductor (CMOS) technology during the late 1980s and the early 1990s. This convergence helped transform passive components into active systems capable of responding to stimuli in real time. MEMS miniaturized sensing elements, while CMOS handled electronic control and data interpretation. The global MEMS market was valued at over $14 billion in 2023, with a notable portion driven by automotive applications, as reported by Yole Group. Now, all new cars have dozens of sensors, many of which owe their existence to advancements initiated more than three decades ago.
Lj Ristic, an electrical engineer, was among the key figures behind such early innovation. What he contributed during his time at Motorola set the pace for how MEMS sensors could be mass-produced, merged with CMOS circuits, and applied reliably in automotive conditions. Ristic’s efforts particularly pioneered the transition from analog sensors to intelligent systems, where real-time sensing of the environment and safety-critical response mechanisms became increasingly commonplace in vehicles.
During the early 1990s at Motorola, Ristic formed a group that commercialized surface micromachined MEMS sensors for safety functions. One of the noted is his invention of differential capacitive accelerometers using multi-layer polysilicon surface micromachining. The sensors were at the heart of airbag deployment, designed to detect rapid deceleration and trigger the inflation mechanism with a high degree of precision. Motorola’s design philosophy differed from competitors like Analog Devices, which employed comb-structure designs. The Motorola strategy, led by Ristic, delivered production-grade quality and reliability, which contributed to MEMS accelerometers becoming more widely adopted in the automotive industry.
Volume production of MEMS-based accelerometers began in 1993. According to IC Insights and the Semiconductor Industry Association (SIA), market analysis indicates that MEMS sensors have grown rapidly to become one of the highest-growth segments in the auto electronics industry. This rapid adoption was made possible by the ability to integrate MEMS sensing and CMOS logic in tightly coupled systems. Ristic developed such hybrid technologies, which allowed for smaller, more efficient, and cost-effective sensor modules. MEMS and CMOS integration became a model for future automobile applications employing gyros, pressure sensors, and eventually optics.
Ristic also contributed to the area of multidimensional magnetic field sensing using lateral bipolar transistor structures as well as Hall devices. This work laid the groundwork for on-chip direction sensing in miniature silicon platforms. Such developments would be of considerable importance not only in vehicle orientation but also in steering, anti-lock braking, and drivetrain feedback. He was granted patents for magnetic field sensors, differential measurement techniques, and integrated signal conditioning, which facilitated the development of subsequent commercial products.
Environmental monitoring employing innovative systems was another core area of activity for Ristic. He is the inventor of the microprocessor with environmental sensing capabilities. This work helped pave the way for future products, such as tire pressure monitoring systems (TPMS), which became federally mandated in many nations, including the United States under the TREAD Act of 2000. TPMS utilize MEMS pressure and accelerometer sensors, a temperature sensor, a microprocessor, and RF receiver and transmitter. The system provides real-time data about tire pressure, as well as other smart data regarding the vehicle’s state.
Apart from the sensor devices themselves, Ristic played a crucial role in enabling the broader design of automotive systems. In the field of optoelectronics, he is at the forefront of leveraging his experience in heterogeneous integration, integrating MEMS Mirrors, lasers, optics, electronics, software, and AI. This work led to the development of a laser-induced dynamic light system for headlamp applications in automobiles. He is also the inventor of a novel Lidar system with laser projection capability for applications in the automotive industry. It is expected that these systems will play a growing role in the safety of future vehicles.
Industry endorsement of Ristic’s work has been reflected in senior roles within established companies as well as new start-ups. Following Motorola, he worked at ON Semiconductor, Alpha Industries, Sirific Wireless, and Crocus. Since 2019, he has been serving as Chief of Business Development and Strategy at Mirrorcle Technologies, a company specializing in MEMS mirror systems for optoelectronic applications.
Though Ristic avoided public light, his name appears in numerous technical journals, conference proceedings, and patent applications. His 1994 book Sensor Technology and Devices, one of the first to address MEMS in a general engineering readership, continues to be cited in scholarship as well as business research. Ristic is a frequently invited speaker, including recently at the 2025 Laser Display and Lighting Conference at Trinity College in Dublin.
In retrospect, the development of smart car systems was not an overnight process, but rather a decades-long series of engineering advancements. The embedding of sensing technology into cars has been made possible by individuals who bridged the fields of materials science, electrical engineering, and industrial design. Ristic’s work on integrating these disciplines — sensor fusion, manufacturing, and platform development — has helped shape the capabilities of intelligent cars today.