Microfabricated calibration tool for direct shear stiffness measurements with applications in cell mechanics

Higgs, G.; Simmons, Chelsey S.; Fried, Andrew T.; Pruitt, Beth L.

doi:10.1109/icsens.2010.5690081

Cited by 2 publications

(3 citation statements)

References 6 publications

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“…We have previously introduced our device and approach as a way to overcome the limitations often encountered when existing microcharacterization tools interface with hydrogels [1], and now we report the full characterization. Soft, hydrated samples are common in biology and biomedical research; however existing approaches and micro-characterization tools face challenges in characterizing hydrated biological materials.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present a microelectromechanical systems (MEMS) electrostatic actuator for shear characterization (ASC; figure 1) that effectively characterizes the microscale shear properties of hydrated samples. We have previously introduced our device and approach as a way to overcome the limitations often encountered when existing microcharacterization tools interface with hydrogels [1], and now we report the full characterization. Soft, hydrated samples are common in biology and biomedical research; however existing approaches and microcharacterization tools face challenges in characterizing hydrated biological materials.…”

Section: Introductionmentioning

confidence: 99%

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MEMS-based shear characterization of soft hydrated samples

Higgs

Simmons

Gao

et al. 2013

J. Micromech. Microeng.

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We have designed, fabricated, calibrated and tested actuators for shear characterization to assess microscale shear properties of soft substrates. Here we demonstrate characterization of dry silicone and hydrated polyethelyne glycol. Microscale tools, including atomic force microscopes and nanoindenters, often have limited functionality in hydrated environments. While electrostatic comb-drive actuators are particularly susceptible to moisture damage, through chemical vapor deposition of hexamethyldisiloxane, we increase the hydrophobicity of our electrostatic devices to a water contact angle 90 ± 3°. With this technique we determine the effective shear stiffness of both dry and hydrated samples for a range of soft substrates. Using computational and analytical models, we compare our empirically determined effective shear stiffness with existing characterization methods, rheology and nanoindentation, for samples with shear moduli ranging from 5-320 kPa. This work introduces a new approach for microscale assessment of synthetic materials that can be used on biological materials for basic and applied biomaterials research.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

MEMS-based shear characterization of soft hydrated samples

Higgs

Simmons

Gao

et al. 2013

J. Micromech. Microeng.

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“…Higgs et al designed and fabricated an electrostatic actuator for direct calibration of hydrogel shear stiffness. 22 The electrostatic actuator is supported by a flexure. We mounted a cantilever oriented perpendicular to the movement of the actuator.…”

Section: B Calibration Of a Mems Electrostatic Actuatormentioning

confidence: 99%

Piezoresistive cantilever force-clamp system

Park

Petzold

Goodman

et al. 2011

Review of Scientific Instruments

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We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or "clamps" the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the builtin capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable realtime controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of μN force and nm up to tens of μm displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

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Microfabricated calibration tool for direct shear stiffness measurements with applications in cell mechanics

Cited by 2 publications

References 6 publications

MEMS-based shear characterization of soft hydrated samples

MEMS-based shear characterization of soft hydrated samples

Piezoresistive cantilever force-clamp system

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