Cross-axis sensitivity reduction of a silicon MEMS piezoresistive accelerometer

Sankar, A. Ravi; Das, Soumen; Lahiri, S. K.

doi:10.1007/s00542-008-0740-y

Cited by 51 publications

(14 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…; Kal et al . ; Sankar, Das & Lahiri ). The sensor is most sensitive to changes in tilt when the axis involved is perpendicular to the acceleration and is least sensitive when it is parallel.…”

Section: Discussionmentioning

confidence: 99%

Simplifying data acquisition in plant canopies‐ Measurements of leaf angles with a cell phone

et al. 2014

View full text Add to dashboard Cite

Summary1. Canopies are complex multilayered structures comprising individual plant crowns exposing a multifaceted surface area to sunlight. Foliage arrangement and properties are the main mediators of canopy functions. The leaves act as light traps whose exposure to sunlight varies with time of the day, date and latitude in a trade-off between photosynthetic light harvesting and excessive or photoinhibitory light avoidance. To date, ecological research based upon leaf sampling has been limited by the available technology, with which data acquisition becomes labour intensive and time-consuming, given the overwhelming number of leaves involved. 2. In the present study, our goal involved developing a tool capable of measuring a sufficient number of leaves to enable analysis of leaf populations, tree crowns and canopies. We specifically tested whether a cell phone working as a 3D pointer could yield reliable, repeatable and valid leaf angle measurements with a simple gesture. We evaluated the accuracy of this method under controlled conditions, using a 3D digitizer, and we compared performance in the field with the methods commonly used. We presented an equation to estimate the potential proportion of the leaf exposed to direct sunlight (SAL) at any given time and compared the results with those obtained by means of a graphical method. 3. We found a strong and highly significant correlation between the graphical methods and the equation presented. The calibration process showed a strong correlation between the results derived from the two methods with a mean relative difference below 10%. The mean relative difference in calculation of instantaneous exposure was below 5%. Our device performed equally well in diverse locations, in which we characterized over 700 leaves in a single day. 4. The new method, involving the use of a cell phone, is much more effective than the traditional methods or digitizers when the goal is to scale up from leaf position to performance of leaf populations, tree crowns or canopies. Our methodology constitutes an affordable and valuable tool within which to frame a wide range of ecological hypotheses and to support canopy modelling approaches.

show abstract

Section: Discussionmentioning

confidence: 99%

Simplifying data acquisition in plant canopies‐ Measurements of leaf angles with a cell phone

et al. 2014

View full text Add to dashboard Cite

show abstract

“…However, when the ratio A/d 2 is increased to improve the Z-axis sensitivity, the damping ratio of the device is also increased as mentioned before. For most of the practical applications of the accelerometer, near critical damping ratio is preferred (Hsu 2002;Ravi Sankar et al 2009b). The damping ratio (f) of the proposed three layer structure can be written from (Chae et al 2005;Yazdi and Najafi 2000) as,…”

Section: Performance Parametersmentioning

confidence: 99%

“…High primeaxis sensitivity, low cross-axis sensitivity and wide bandwidth are few of the desired properties of microaccelerometers. For practical applications using accelerometers, a near critical damping ratio of 0.7 is preferred (Hsu 2002;Ravi Sankar et al 2009b) since it provides better system performance in terms of rise time, peak-overshoot, delay time, settling time and flat frequency response. To achieve good sensitivity in capacitive accelerometers, the gap between the parallel plates should be extremely small.…”

Section: Introductionmentioning

confidence: 99%

Coupled effects of gold electroplating and electrochemical discharge machining processes on the performance improvement of a capacitive accelerometer

2011

Self Cite

View full text Add to dashboard Cite

Coupled effects of an electroplated gold layer and damper holes drilled by Electro Chemical Discharge Machining (ECDM) process on the performance improvement of a quad beam capacitive accelerometer is presented in this paper. A simple quad beam-proof mass configuration with its beams located symmetrically at the centre of all the edges of the proof mass and connected to an outer supporting frame is considered in the present study. For a fixed damping ratio, prime-axis sensitivity of the sensor is increased by the damper holes whereas an electroplated gold layer improves the prime-axis sensitivity, cross-axis sensitivity, and Brownian Noise Equivalent Acceleration (BNEA). Moreover, the increased weight of the proof mass due to an electroplated gold layer further reduces the damping of the device which in turn helps to increase the prime-axis sensitivity more. A new figure of merit called Performance Factor (PF), defined as the ratio of the product of the primeaxis sensitivity and resonant frequency to the cross-axis sensitivity at a fixed damping ratio of 0.7 is used as a quantitative index to evaluate the performance improvement caused by the coupled effects of gold electroplating and ECDM processes. Simulation results show that for a device with damper holes of 8 lm diameter and electroplated gold layer of dimensions 3,000 lm 9 3,000 lm 9 20 lm, the prime-axis sensitivity is increased by more than 500 times, rotational cross-axis sensitivity and BNEA are reduced by around 10 and 30%, respectively and the PF is improved by around 482 times at a fixed damping ratio of 0.7.

show abstract

“…Linearity is ensured by high stiffness in crossdirections and additional beams. Many publications can be found for the double-clamped beam topology (Dong et al 2007;Chen et al 2008;Amarasinghe et al 2007;Tran et al 2008;Takao et al 2001;Sankar et al 2008).…”

Section: Double-clamped Beam Topologymentioning

confidence: 99%

Miniaturization limits of piezoresistive MEMS accelerometers

et al. 2009

View full text Add to dashboard Cite

We present the miniaturization limits of axially loaded piezoresistive MEMS accelerometers. Therefore we identify limiting factors on the basis of FEM-verified analytical models. To ensure a broad discussion we compare two different axially loaded topologies: first a conventional topology, which can be manufactured already today, and second a future-oriented topology utilizing nanowires. To enable a realistic comparison of the different topologies we shrink the sensor while maintaining a specific performance (e.g. sensitivity and noise) considering design limitations such as fracture of silicon and buckling. To find the minimum total sensor area under certain constraints and therefore the optimal geometric and material parameters we apply optimization techniques to our analytical models. It will be seen that the piezoresistive transducer principle for MEMS accelerometers has a promising shrink potential with minimum total sensor dimensions as low as 150 9 150 9 10 lm 3 achievable by use of currently available manufacturing processes.

show abstract

Cross-axis sensitivity reduction of a silicon MEMS piezoresistive accelerometer

Cited by 51 publications

References 29 publications

Simplifying data acquisition in plant canopies‐ Measurements of leaf angles with a cell phone

Simplifying data acquisition in plant canopies‐ Measurements of leaf angles with a cell phone

Coupled effects of gold electroplating and electrochemical discharge machining processes on the performance improvement of a capacitive accelerometer

Miniaturization limits of piezoresistive MEMS accelerometers

Contact Info

Product

Resources

About