New Sensor Design for Early Single-Cell Cancer Diagnosis
ECE Assistant Professors Siddhartha Ghosh, Marco Colangelo, and Associate Professor Cristian Cassella published their research on “Topologically enhanced guided acoustic wave sensors” in Physical Review Applied.
From magnetic bits in next-generation supercomputers to individual cancer cells requiring early diagnosis, society’s need to detect ever-smaller targets is rapidly growing. Over the past decades, numerous sensors based on micro- and nanoelectromechanical devices have emerged, offering unique advantages for inertial, chemical, and other types of sensing. However, these devices typically suffer from a fundamental limitation: when tasked with detecting parameters localized within just a few square micrometers, they exhibit either poor sensitivity or poor resolution.
Researchers from Northeastern University and Politecnico di Milano have developed a breakthrough sensor design that recreates exotic features originally discovered in topological systems within condensed matter physics, enabling the detection of highly localized parameters of interest with unprecedented sensitivity and resolution.
Their device, termed the topological guided acoustic wave (tGAW) sensor, overcomes the long-standing trade-off that plagues conventional micro- and nanoelectromechanical sensors: reducing the device’s dimensions improves sensitivity to localized parameters but simultaneously increases noise, thereby degrading the limit of detection. The tGAW sensor circumvents this trade-off by demonstrating piezoelectric transduction of topological interface states at the microscale. These states can confine and concentrate energy within a miniaturized region without requiring the entire device to be miniaturized—thus avoiding the performance and power-handling degradations associated with scaling, which otherwise lead to higher thermomechanical noise in conventional devices.
The research team demonstrated the tGAW device for infrared sensing, achieving more than a fourfold increase in sensitivity to absorbed power and over two orders of magnitude improvement in the limit of detection compared to conventional (non-topological) vibration modes.
This work opens new possibilities for chip-scale sensors in emerging applications that demand the detection of highly localized parameters, including early cancer diagnosis through single-cell analysis, readout of high-density magnetic memory devices, and the development of more sensitive infrared camera pixels for security and environmental monitoring.
Abstract:
Piezoelectric microelectromechanical guided acoustic wave (GAW) sensors are widely used across a range of applications, from inertial sensing to environmental and chemical sensing. These devices typically rely on the resonance frequency of a Lamb mode as readout parameter, making them well suited for detecting parameters of interest (PoIs) that act over their entire vibrating structure. However, this approach is less effective for monitoring localized PoIs. To address this limitation, prior efforts have focused on miniaturizing GAW sensors. While this miniaturization strategy permits us to enhance responsivity to localized PoIs, it also causes a degradation of the limit of detection (LoD). In this paper, we present a GAW sensor for localized PoIs that overcomes the trade-off between responsivity and limit of detection by leveraging topological interface states (ISs). We demonstrate the effectiveness of our approach by sensing the infrared (IR) power emitted by a laser with a 5-μm-diameter beam size, focused on the interface at which the IS is transduced. Our results show that harnessing ISs yields significantly higher responsivity to IR power (𝑅 =835 Hz/μW) and a 2 orders of magnitude better limit of detection (LoDtm =79 fW/√Hz) compared to conventional Lamb modes. Our findings pave the way for deploying GAW sensors in emerging applications that require monitoring localized parameters, such as proteomics, spintronics, mass spectroscopy, and more.