The constant development and miniaturization of MEMS sensors invariably provides new possibilities for their use in health-related and medical applications. The application of MEMS devices in posturographic systems allows faster diagnosis and significantly facilitates the work of medical staff. MEMS accelerometers constitute a vital part of such systems, particularly those intended for monitoring patients with imbalance disorders. The correct design of such sensors is crucial for gathering data about patient movement and ensuring the good overall performance of the entire system. This paper presents the design and measurements of a three-axis accelerometer dedicated for use in a device which tracks patient movement. Its main focus is the characterization of the sensor, comparing different designs and evaluating the impact of the packaging and readout circuit integration on sensor operation. Extensive testing and measurements confirm that the designed accelerometer works correctly and allows identifying the best design in terms of sensitivity/stability. Moreover, the response of the proposed sensor as a function of the applied acceleration demonstrates very good linearity only if the readout circuit is integrated in the same package as the MEMS sensor.

Designing of MEMS devices requires modeling step. Many devices combines mechanical and electrical domains. Very often it is desired to use one simulation tool that allows taking into account both domains. Such functionality has CADENCE environment. In this paper we do such simulations using developed macro model of capacitive MEMS accelerometer. The accelerometer is described in Verilog-A language and placed in electrical schematic that consist of read-out circuit. The simulations were performed for the device z-axis CMOS-integrated acceleration sensor that has been developed in UPC Barcelona. The results of simulations were compared to those obtained by measurements of fabricated device.

Electro-thermal models are commonly used in simulations and designing MEMS devices, also in case of microbolometers. These models allow to estimate sensors performance before fabrication that consequently impacts on fabrication cost. Coupling of electric and thermal domains and building appropriate model for carrying out simulations are crucial to detect all phenomena having impact for Readout Integrated Circuit. This article brings closer to the subject matter of circuit modelling (willingly implemented in MATLAB/SIMULINK or PSPICE tools) and to its theoretical background.

In this work, we analysed the difference between the measurement and simulation results of thermal drift of a custom designed capacitive MEMS accelerometer. It was manufactured in X-FAB XMB10 technology together with a dedicated readout circuit in X-FAB XP018 technology. It turned out that the temperature sensitivity of the sensor’s output is nonlinear and particularly strong in the negative Celsius temperature range. It was found that the temperature drift is mainly caused by the MEMS sensor and the influence of the readout circuit is minimal. Moreover, the measurements showed that this temperature dependence is the same regardless of applied acceleration. Simulation of the accelerometer’s model allowed us to estimate the contribution of post-manufacturing mismatch on the thermal drift; for our sensor, the mismatch-induced drift accounted for about 6% of total thermal drift. It is argued that the remaining 94% of the drift could be a result of the presence of residual stress in the structure after fabrication.