In the realm of commercial and defense systems, there is a growing need for sensors that can withstand and operate in extreme thermal environments. Currently, many high-performance physical sensors are limited by their inability to function effectively in these harsh conditions. As a result, systems are often designed with reduced performance and excessive margins to account for uncertain conditions. However, the Defense Advanced Research Projects Agency (DARPA) is addressing this challenge through its High Operational Temperature Sensors (HOTS) program. The HOTS program aims to develop sensor microelectronics capable of operating at high temperatures, enabling closed-loop operation and state-of-health monitoring in extreme environments.
The Need for High-Temperature Sensors
Numerous industries, such as oil and gas, geothermal, automotive, turbine, and hypersonic systems, require sensors that can endure thermal environments beyond the capability of current high-performance sensors. These systems must navigate uncertain conditions and harsh thermal environments, often resulting in reduced performance and increased safety margins. The inability to monitor system conditions accurately limits optimization and efficiency in these critical applications.
Microelectronic sensors, which combine transducers and signal-conditioning microelectronics, are an ideal solution for high-bandwidth and large-dynamic-range requirements. However, existing technologies are limited to low-temperature zones (<225 °C) due to material constraints. For example, turbine engines, a common application for high-temperature sensors, operate at elevated temperatures that exceed the capabilities of current sensors.
To overcome this limitation, DARPA launched HOTS program in May 2023 that seeks to develop sensors that can operate at temperatures as high as 800 °C.
“Many of the defense and industrial systems that rely on sensors experience harsh environments beyond the capability of today’s high-performance physical sensors. That means these systems have to be designed and operated with reduced performance and excessive margins – they’re limited by the uncertainty of their thermal environments,” said Dr. Benjamin Griffin, program manager for HOTS. “However, if we can design, integrate, and demonstrate high-performance physical sensors that can operate in high-temperature environments, we can advance toward systems that perform at the edge of their capability instead of the limits of uncertainty.”
Objectives of the HOTS Program
The objective of the HOTS program is to develop sensor microelectronics consisting of transducers, signalconditioning microelectronics, and integration that operate with high bandwidth (>1 MHz) and dynamic range (>90 dB) at extreme temperatures (i.e., at least 800 °C). Performance will be validated through the development and demonstration of a pressure sensor module consisting of integrated transducer and signal-conditioning microelectronics.
To achieve this goal, the program focuses on the following key areas:
- Long-Lifetime and Large-Bandwidth Transistors: The HOTS program aims to achieve the development of transistors capable of withstanding high temperatures while maintaining long lifetimes and large bandwidths. Advancements in wide-bandgap transistors have shown promise in overcoming the material limitations associated with elevated temperatures.
- High-Sensitivity Transducers: The program seeks to develop transducers with high sensitivity that can operate reliably in extreme temperature environments. By leveraging thermally robust transducer materials, researchers aim to enhance the sensor’s performance at high temperatures.
- Integration without Performance Degradation: Integrating a high-operating temperature sensor into a complete system without sacrificing performance is a crucial aspect of the program. Heterogeneous integration techniques and insights from various domains of expertise will play a vital role in achieving this objective.
The HOTS program will leverage recent advances in wide-bandgap transistors, demonstrations of thermally robust transducer materials, and insight from heterogeneous integration techniques to overcome the technical challenges and form highly-integrated, thermally-hardened sensors.
Collaboration for Success
To accomplish the ambitious goals of the HOTS program, DARPA recognizes the need for collaboration among various entities. The program encourages partnerships between academia, small businesses, national laboratories, and the defense industrial base research community. The diverse expertise available across these sectors is instrumental in addressing the technical challenges associated with developing highly-integrated and thermally-hardened sensors.
The HOTS program, initiated by DARPA, aims to revolutionize sensor technology by developing microelectronics capable of operating in extreme thermal environments. By enabling sensors with high bandwidth and dynamic range at temperatures exceeding 800 °C, this program has the potential to unlock new possibilities for industries reliant on accurate monitoring and closed-loop operations. The collaboration between different entities is crucial in overcoming technical challenges and achieving the program’s objectives. With the advancements expected from the HOTS program, we can anticipate improved system performance, enhanced efficiency, and increased safety in critical applications across a wide range of industries.