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We have designed and built a fast and precise balanced polarimeter from components commonly found in undergraduate physics laboratories. Balanced polarimetry measures the orientation of linearly polarized light by splitting the beam into orthogonal polarization components and detecting each separately. Our polarimeter is capable of measuring the orientation of linearly polarized light with a precision of approximately 0.001°/Hz. The apparatus cost less than $1000. Measurements of the specific rotation of sucrose and of the Faraday effect were performed, both of which produced results that were comparable to previously reported values.

Although high strain and strain-rate impacts to the human body have been the subject of substantial research at both the systemic and tissue levels, little is known about the celllevel ramifications of such assaults. This is largely due to the lack of high throughput, dynamic compression devices capable of simulating such traumatic loading conditions on individual cells. To fill this gap, we developed and characterized a high speed, high actuation force, magnetically driven MEMS chip to apply stress to biological cells at unprecedented strain (10% to 90%), strain rate (30,000 to 200,000 s −1), and throughput (12,000 cells/min). To demonstrate the capabilities of the µHammer, we applied biologically relevant strains and strain rates to human leukemic K562 cells and then monitored their viability for up to 8 days. We observed significantly repressed proliferation of the hit cells compared to both unperturbed and sham-hit control cells, accompanied by minimal cell death. This indicates success in applying cellular damage without compromising the overall viability of the population, allowing us to conclude that this device is well suited to study the subtle effects of impact on large populations of inherently heterogeneous cells.

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We report the application of stress to biological cells at unprecedented strain (50%), strain rate (180,000 s -1 ), and throughput (1,800 cells/min) using a high-speed, high actuation force magnetically-driven MEMS chip. This device is uniquely suited to study the effects of impact on large populations of inherently heterogeneous cells, enabling statistical analysis that can elucidate the cell-level ramifications of Traumatic Brain Injury (TBI). To demonstrate the capabilities of the µHammer, we applied TBIrelevant strains and strain rates to human leukemic K562 cells then monitored their proliferation for 9 days. We observed significantly repressed proliferation of the hit cells compared to both the negative and sham controls, indicating success in applying sublethal cellular damage.