Biomimetic diamond MEMS sensors based on odorant-binding proteins - Sensors validation through an autonomous electronic system

At a Glance

Metadata	Details
Publication Date	2017-05-01
Authors	Maira Possas-Abreu, Lionel Rousseau, Farbod Ghassemi, Gaëlle Lissorgues, Massiel Habchi
Institutions	Laboratoire d’électronique, systèmes de communication et microsystèmes, CEA LIST
Citations	12
Analysis	Full AI Review Included

Technical Documentation & Analysis: Biomimetic Diamond MEMS Sensors

6CCVD Analysis Reference: CEA-01809228 (Possas-Abreu et al., 2017) Application Focus: Biomimetic Diamond Micro-Cantilever Sensors for Electronic Olfaction (E-Nose)

Executive Summary

This research validates the use of Polycrystalline Diamond (PCD) micro-cantilevers as robust transducers for biomimetic odor sensors, leveraging diamond’s superior bio-interface properties and stability.

Core Value Proposition: Successful demonstration of a fully integrated, electronically readable diamond MEMS sensor array functionalized with Odorant Binding Proteins (OBPs).
Material Achievement: Polycrystalline Diamond (PCD) was chemically functionalized using a low-temperature diazonium grafting method (<4°C), preserving integrated piezoresistive gauges.
Detection Mechanism: Sensors operate in dynamic mode, detecting mass loading (IBMP binding) via a shift in resonance frequency (f=85 kHz).
Performance Metric: A clear frequency shift of approximately 40 Hz was measured upon exposure to saturated 2-isobutyl-3-methoxypyrazine (IBMP) vapor.
System Integration: The study confirms the feasibility of combining diamond’s long-term bio-stability with integrated electronic read-out, eliminating the need for complex, costly external optical systems.
Future Potential: This approach is highly promising for developing miniaturized, parallelizable, and reliable electronic nose (e-nose) systems and general vapor sensing applications.

Technical Specifications

The following hard data points were extracted from the research paper detailing the sensor geometry, performance, and experimental parameters.

Parameter	Value	Unit	Context
Cantilever Dimensions	310 x 140	µm	Length x Width
Resonance Frequency (f)	85000	Hz	Typical, measured in air before grafting
Quality Factor (Q)	600	N/A	Measured in air
OBP Grafting Temperature	<4	°C	Required to preserve integrated electronics
OBP Solution Concentration	1.0	mg/mL	Used for immobilization
OBP Exposure Time	2	hours	Time exposed to OBP solution
Reference Analyte	2-isobutyl-3-methoxypyrazine (IBMP)	N/A	Used due to high affinity with porcine OBP
Sensor Response (ΔFreq)	~40	Hz	Frequency shift upon saturated IBMP exposure
Estimated Bound Molecules	10⁸	Molecules	IBMP molecules bound to immobilized OBPs
Fluorescence Excitation (λ_exc)	550	nm	Used for OBP visualization

Key Methodologies

The experiment successfully combined standard MEMS fabrication with a novel low-temperature chemical functionalization technique compatible with integrated electronics.

Diamond Cantilever Fabrication: Polycrystalline diamond micro-cantilevers were fabricated using established processes, designed for dynamic mode operation and incorporating integrated piezoresistors for strain-sensing.
Surface Preparation: Diamond micro-cantilevers were cleaned prior to functionalization.
Diazonium Salt Activation: The chemical grafting process utilized in situ formation of nitrous acid (HNO₂) by adding sodium nitrite (NaNO₂) in an acid medium (0.5 M HCl).
Radical Formation: The nitrous acid reacted with phenylenediamine (NH₂-φ-NH₂) to form the diazonium function (N₂⁺). This function was removed in gaseous form, generating a radical phenyl capable of reacting with the diamond surface (C-C covalent bonds).
Grafting Completion: 4-aminobenzoic acid (NH₂-φ-COOH) was used to complete the grafting process, preparing the surface for protein attachment.
OBP Immobilization: Porcine OBPs (1.0 mg/mL in 20 mM PBS, pH=8.00) were exposed to the cantilevers for 2 hours at low temperatures (<4°C). This low temperature was critical to preserve the integrated piezoresistive gauges.
Electronic Validation: Sensors were placed in a customized stainless steel gas analysis cell (8 cavities) and monitored by a dedicated, autonomous electronic system designed for low-noise signal generation and analog processing.

6CCVD Solutions & Capabilities

This research highlights the critical need for high-quality, customizable MPCVD diamond substrates that can withstand complex chemical processing and integrate seamlessly with microelectronics. 6CCVD is uniquely positioned to supply the materials and services required to replicate, scale, and advance this research into commercial e-nose systems.

Research Requirement	6CCVD Solution & Capability	Technical Advantage for Replication/Scaling
Material Base (Polycrystalline Diamond)	High-Purity MPCVD PCD Wafers	We supply optical and electronic grade PCD substrates up to 125mm, providing the stable carbon sp³ surface essential for robust, long-term bio-receptor immobilization (Ref. [7]).
MEMS Integration (Piezoresistors/Readout)	Custom Metalization Services	6CCVD offers internal deposition of Au, Pt, Pd, Ti, W, and Cu. This capability is crucial for fabricating integrated piezoresistive strain gauges and contact pads directly onto the diamond surface, compatible with subsequent low-temperature bio-grafting.
Cantilever Dimensions (310 µm x 140 µm)	Precision Laser Cutting & Etching	We provide precision dicing and laser cutting services, ensuring the exact micro-scale geometries and high aspect ratios required for dynamic mode MEMS sensors, minimizing material waste and maximizing yield.
Surface Quality (For uniform grafting)	Advanced Polishing Services	Our PCD substrates are polished to an industry-leading roughness of Ra < 5nm (for inch-size plates), guaranteeing the surface uniformity necessary for consistent chemical functionalization and reliable sensor array performance.
Thickness Control (MEMS Layer)	SCD/PCD Thickness Control (0.1µm - 500µm)	We offer precise control over the diamond layer thickness, vital for tuning the cantilever’s mechanical properties (resonance frequency, Q-factor) to optimize sensitivity for specific mass loading applications.
Engineering Support (Bio-MEMS/E-Nose)	In-House PhD Engineering Team	Our experts can assist researchers in selecting the optimal diamond material (e.g., specific nitrogen incorporation levels) and surface termination for advanced bio-grafting techniques like diazonium activation, accelerating development cycles for similar Biomimetic Sensor projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Conference of 2017 ISOCS/IEEE International Symposium on Olfaction and Electronic Nose, ISOEN 2017 ; Conference Date: 28 May 2017 Through 31 May 2017; Conference Code:129051

Tech Support

Original Source

DOI: https://doi.org/10.1109/isoen.2017.7968909

References

2008 - Covalent grafting onto self-adhesive surfaces based on aryldiazonium salt seed layers [Crossref]
2014 - Grafting odorant binding proteins on diamond bio-MEMS [Crossref]