Bio/chemical sensors heterogeneously integrated with Si-CMOS circuitry

Abstract

Sensor arrays for bio/chemical sensing generally incorporate different types of sensors with different substrate coatings, enabling increased sensor sensitivity and selectivity. However, a challenge in using multiple sensor systems is integration with RF electronic circuitry. This work presents the development of flexural plate wave (FPW) acoustic devices implemented in a sensor array and co-integrated on a Si-CMOS circuit. FPWs are highly sensitive to surface perturbations and indirectly sense analytes by detecting mass changes on the sensing plate surface. The sensors are placed in an oscillating circuit, where changes in the oscillation frequency are used to determine changes in the wave velocity due to mass loading by the analyte [1, 2]. Since FPWs are generated in thin plates, these devices are highly sensitive to loading and exhibit the highest mass sensitivities of any acoustic wave device [1,2]. In the work presented, FPWs are fabricated on Si/SiO 2 /Si native substrates, with the interdigitated transducers (IDTs) isolated from the active sensing surface. This innovative design enables the sensors to be fabricated and then separated from the native substrate, transferred, and bonded to the host Si-CMOS circuit. Thus, a new approach for the heterogeneous integration of FPW sensors and circuitry is provided. Following integration, the FPWs can be customized with either chemical membranes or biological functionalization. Moreover, this novel approach allows each sensor to be optimized independently before being connected to the host substrate. This paper presents the design, development, and integration process of an FPW sensor on Si-CMOS circuitry. KEYWORDS: Bio/chemical sensors, heterogeneous integration, acoustic wave devices INTRODUCTIONA bio/chemical sensor can be defined as a device that converts a biological/chemical state into a measurable signal. The bio/chemical sensing process involves molecular recognition of a biological and chemical species and transduction of the biological or chemical information into a measurable signal. Bio/chemical sensors have been used to detect and measure essential information about the state of our environment. Furthermore, in the area of clinical analysis, there is a need for reliable biological sensors that can provide fast and accurate answers to the diagnostic demands of medical care attendants. The threat of terrorism via chemical warfare agents (CWAs) also requires the use of bio/chemical sensors for crucial detection and sensing capabilities. Many sensors have been described in the literature for such applications [1][2][3][4][5][6][7]. They include electrochemical sensors, chemi-resistors and capacitors, metal-oxide gas sensors, field effect transistor (FET) sensors, calorimetric sensors, and acoustic wave sensors [1][2][3][4][5][6][7].

Measurement of the Surface Recombination Velocity in Organically Functionalized Silicon Nanostructures: The Case of Silicon on Insulator

“…The development of hybrid devices interfacing silicon to molecules has gained a lot of interest over the past 10 years as a route to obtain small devices with new applications. The size of the active element can be dictated by the structure chosen (flat Si crystals, , nanoporous Si, Si nanopowder/quantum dots, Si nanowires, and so forth), and the properties of the device are tuned by the molecule properties (redox compound for charge storage media/nanoelectronics, photosensitive compounds for photovoltaics, optical devices, coordination chemistry compounds for sensor, biological systems for nanoelectronics, or nanobiotechnology). In such a field, the interface between the inorganic substrate and the organic compound plays a key role in the device properties and stability over time.…”