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The metabolism of cells is studied by scientists using a number of cells high enough to have a signal in the regular differential scanning calorimetry (DSC). Currently the number of cells necessary for thermal analysis is on the order of hundreds of thousands. The cell metabolism researchers have been trying to reduce this number with an eye on the final prize of sample size of one. In this paper, we report a novel MEMS_DSC (Micro Electro Mechanical System-Differential Scanning Calorimetry), which reduces the number of cells needed for analysis by about two orders of magnitude. It uses the Seebeck effect generated by a polysilicon n-gold junction to convert the temperature measured from cells directly into a voltage signal. To characterize the device a laser was used to heat the sensor; a lock-in amplifier, coupled with an optical chopper, allowed us to measure a very low heat power (25.5 nW).

Micromechanical systems are increasingly being used as tools in biological applications, since their characteristic dimensions permit to operate at the same length scale of the structures under investigation. Here, we present a methodology for the design, fabrication and operation of a tool for the assessment of mechanical properties of single cells. In particular, we describe a microsystems platform to study bio-mechanical response of single living cells to in-plane biaxial stretching. The proposed device employs a new linkage design in order to obtain the displacement of the quadrants of a sliced circular plate in mutually-orthogonal directions using just one linear actuator. With this linkage geometry, the whole device has only one degree of freedom. This results in a very predictable and reliable mechanical behaviour, thereby allowing use a simple and easily available control electronics. Results of this study have relevance for the design of a powerful yet simple BioMEMS platform for the characterization of living cells as in-plane bi-axial loading simulated the conditions experienced by cells in vivo more realistically than a uniaxial stretching.

Taking advantage of an off-the-shelf, high-quality but inexpensive optical detector, namely a DVD optical head, a system has been developed for the dynamic characterization of the vertical (out-of-plane) displacement of MEMS structures. The novelty of the proposed setup, besides the proposed field of application, lies in the ability of the system to operate both in air and in a liquid environment. In order to give a representative experimental proof of the functionality of the system, a cantilever array was designed and fabricated via a commercially available multi-user polysilicon surface micromachining process (PolyMUMPs). The frequency response of a tiny silicon cantilever beam (150 µm length, 10 µm width and 1.5 µm thickness) was measured, both in air and in deionized water, and compared against theoretical models of the system. Despite the low-cost signal conditioning system used, it was possible to trace a very clear Bode plot, and to obtain good agreement between experimental data and theoretical predictions. The measurements indicate that this displacement sensor performs very well under many circumstances of interest which require continuous monitoring with large bandwidth. This sensor offers a good low-cost measurement solution for the single-point dynamic characterization of the MEMS devices, particularly when the frequencies involved are high and the working environment is unsuitable for other types of detectors.