Measurement of Compressive Stress-Strain Response at Small-Strains

Our protocol addresses the lack of low-cost, reputable compression testing methods in the small-strain, low-force region. Technologies currently used to advance research include MEMS-based testers, nanoindentation, and custom microscale compression systems for precise small-strain material characterization. Current experimental challenges include achieving accurate force-displacement measurement, reliable calibration, and minimizing noise in small-strain, low-force microscale experiments.

To begin, place the PDMS sample on the force sensor within the compression test setup. Align the moving part perpendicular to the force sensor and center it over the sample to ensure a normal compressive load is applied. Set the drive speed to the previously validated value using the controller interface.

Drive the moving part axially downward along the Z-axis using the motor controller to apply a compressive load to the sample. Measure the compressive force transmitted to the sample in real time using the force sensor mounted underneath. Observe and record the deformation of the sample during compression using a digital microscope.

The error rate between the MS and MTS force measurements was within 2%confirming the accuracy and reliability of the MS.The displacement errors of the linear actuator at drive speeds of 0.5 micrometer per second was minus 0.1%One micrometer per second was plus 0.1%And 10 micrometers per second was plus 0.04%The stress-strain responses of the scaled-down samples measured using the MS and MTS differed by less than 2%supporting the reliability of the MS.Our findings provide a validated, accessible platform for small-strain testing, accelerating material evaluation and device optimization in MEMS and microneedles. Future research will focus on extending for syringes, testing diverse polymers, and quantifying how tension, compression, or symmetry affect modulus estimates.