A Low Spring Constant Piezoresistive Microcantilever for Biological Reagent Detection

Area of Science:

• Materials Science
• Nanotechnology
• Biosensing

Background:

• Piezoresistive microcantilevers are crucial for sensitive detection.
• Developing microcantilevers with low spring constants enhances sensitivity.
• Titanium (Ti) and polyimide (PI) offer promising piezoresistive and mechanical properties.

Purpose of the Study:

• To introduce a novel piezoresistive microcantilever with a low spring constant.
• To develop a microcantilever aptasensor for detecting ricin.
• To evaluate the sensor's performance in terms of sensitivity, reliability, and specificity.

Main Methods:

• Fabrication of a microcantilever using titanium (Ti) as the piezoresistor, a polyimide (PI) layer, and silicon oxide (SiO2) layers.
• Characterization of mechanical properties, including spring constant and deflection sensitivity.
• Development of a Wheatstone bridge configuration with four microcantilevers for stable output.
• Functionalization of the microcantilever surface with a ricin aptamer probe for specific binding.
• Detection of ricin at various concentrations (10-100 ng/mL) and specificity testing using bovine serum albumin (BSA).

Main Results:

• Achieved excellent mechanical performance with a spring constant of 0.02128 N/m and deflection sensitivity of 1.03 × 10^-7 nm^-1.
• Demonstrated low output voltage fluctuation (< 3 μV@3 V) in a phosphate-buffered saline (PBS) environment.
• Successfully detected ricin at concentrations of 10, 20, 50, and 100 ng/mL.
• Confirmed good specificity using BSA as a blank control.

Conclusions:

• The developed Ti and PI-based piezoresistive microcantilever exhibits high sensitivity and reliability.
• The microcantilever aptasensor shows great potential for ultrasensitive biochemical molecule detection.
• This technology is promising for applications requiring specific and reliable detection of biomolecules.