[paper] integrated PD SOI CMOS microcantilever biosensor

Yi Liu, Yuan Tian, Cong Lin, Jiahao Miao & Xiaomei Yu*

A monolithically integrated microcantilever biosensor 

based on partially depleted SOI CMOS technology

Microsystems & Nanoengineering volume 9, Article number: 60 (2023)

DOI: 10.1038/s41378-023-00534-y

* School of Integrated Circuits, Peking University, National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Beijing, 100871, China

Abstract: This paper presents a monolithically integrated aptasensor composed of a piezoresistive microcantilever array and an on-chip signal processing circuit. Twelve microcantilevers, each of them embedded with a piezoresistor, form three sensors in a Wheatstone bridge configuration. The on-chip signal processing circuit consists of a multiplexer, a chopper instrumentation amplifier, a low-pass filter, a sigma-delta analog-to-digital converter, and a serial peripheral interface. Both the microcantilever array and the on-chip signal processing circuit were fabricated on the single-crystalline silicon device layer of a silicon-on-insulator (SOI) wafer with partially depleted (PD) CMOS technology followed by three micromachining processes. The integrated microcantilever sensor makes full use of the high gauge factor of single-crystalline silicon to achieve low parasitic, latch-up, and leakage current in the PD-SOI CMOS. A measured deflection sensitivity of 0.98 × 10−6 nm−1 and an output voltage fluctuation of less than 1 μV were obtained for the integrated microcantilever. A maximum gain of 134.97 and an input offset current of only 0.623 nA were acquired for the on-chip signal processing circuit. By functionalizing the measurement microcantilevers with a biotin-avidin system method, human IgG, abrin, and staphylococcus enterotoxin B (SEB) were detected at a limit of detection (LOD) of 48 pg/mL. Moreover, multichannel detection of the three integrated microcantilever aptasensors was also verified by detecting SEB. All these experimental results indicate that the design and process of monolithically integrated microcantilevers can meet the requirements of high-sensitivity detection of biomolecules.

FIG: a) Micrograph of the fabricated integrated microcantilever sensor IC.
b) SEM photograph of the microcantilever array

Acknowledgements: This research was funded by the National Natural Science Foundation of China (Grant No. 61935001).

Open Access: this article is licensed under a Creative Commons Attribution 4.0 International License 

[paper] Cantilever with Carbon Piezoresistor

Jongmoon Jang, Giulia Panusa, Giovanni Boero and Juergen Brugger 

SU-8 Cantilever with Integrated Pyrolyzed Glass-Like Carbon Piezoresistor

Microsyst Nanoeng 8, 22 (2022)

DOI:10.1038/s41378-022-00351-9

Abstract: Glass-like carbon (GC) is a nongraphitizing material composed entirely of carbon atoms produced from selected organic polymer resins by controlled pyrolysis in an inert atmosphere. The GC properties are a combination of the properties of glass, ceramic, and graphite, including hardness, low density, low thermal conductivity, high chemical inertness, biocompatibility, high electrical conductivity, and microfabrication process compatibility. Despite these unique properties, the application of GC in mechanical sensors has not been explored thus far. Here, we investigate the electrical, structural, and chemical properties of GC thin films derived from epoxy-based negative photoresist SU-8 pyrolyzed from 700 to 900°C. In addition, we fabricated microGC piezoresistors pyrolyzed at 700 and 900 °C and integrated them into nonpyrolyzed SU-8 cantilevers to create microelectromechanical systems (MEMS) mechanical sensors. The sensitivities of the GC sensor to strain, force, surface stress, and acceleration are characterized to demonstrate their potential and limits for electromechanical microdevices.

Fig: Design and layout of the glass-like carbon (GC)-based sensor:

a.) Schematic drawing of the GC strain sensor, and

b.) Enlarged optical microscopic image of a fabricated GC piezoresistor

Acknowledgements: The authors thank the Center of Micro/Nanotechnology (CMi) of EPFL for the microelectromechanical system (MEMS) fabrication support and Bio-Micro Robotics laboratory with Professor Hongsoo Choi of DGIST for the microforce probe system facility support. This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Project “MEMS 4.0”, ERC-2016-ADG, Grant Agreement No. 742683) and the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2020R1F1A107422211).

[paper] 3D integrated GaN/RF-SOI SPST switch

Frédéric Drillet, Jérôme Loraine, Hassan Saleh, Imene Lahbib, Brice Grandchamp, Lucas Iogna-Prat, Insaf Lahbib, Ousmane Sow, Albert Kumar and Gregory U'Ren 

RF Small and large signal characterization of a 3D integrated GaN/RF-SOI SPST switch 

International Journal of Microwave and Wireless Technologies, pp. 1–6, 2021.

*X-FAB France, Corbeil-Essonnes (F)

Abstract: This paper presents the radio frequency (RF) measurements of an SPST switch realized in gallium nitride (GaN)/RF-SOI technology compared to its GaN/silicon (Si) equivalent. The samples are built with an innovative 3D heterogeneous integration technique. The RF switch transistors are GaN-based and the substrate is RF-SOI. The insertion loss obtained is below 0.4 dB up to 30 GHz while being 1 dB lower than its GaN/Si equivalent. This difference comes from the vertical capacitive coupling reduction of the transistor to the substrate. This reduction is estimated to 59% based on a RC network model fitted to S-parameters measurements. In large signal, the linearity study of the substrate through coplanar waveguide transmission line characterization shows the reduction of the average power level of H2 and H3 of 30 dB up to 38 dBm of input power. The large signal characterization of the SPST shows no compression up to 38 dBm and the H2 and H3 rejection levels at 38 dBm are respectively, 68 and 75 dBc.

Fig: X-FAB 3D integration proposal cross-section (left) and the picture of a GaN coupon (right).

Acknowledgement: We would like to acknowledge the Nano2022 program for partially funding this work.

Supplementary material: The supplementary material for this article can be found at DOI: 0.101/1759078721000076