DYSKIMOT: An Ultra-Low-Cost Inertial Sensor to Assess Head’s Rotational Kinematics in Adults during the Didren-Laser Test

Abstract

Various noninvasive measurement devices can be used to assess cervical motion. The size, complexity, and cost of gold-standard systems make them not suited to clinical practice, and actually difficult to use outside a dedicated laboratory. Nowadays, ultra-low-cost inertial measurement units are available, but without any packaging or a user-friendly interface. The so-called DYSKIMOT is a home-designed, small-sized, motion sensor based on the latter technology, aiming at being used by clinicians in “real-life situations”. DYSKIMOT was compared with a gold-standard optoelectronic system (Elite). Our goal was to evaluate the DYSKIMOT accuracy in assessing fast head rotations kinematics. Kinematics was simultaneously recorded by systems during the execution of the DidRen Laser test and performed by 15 participants and nine patients. Kinematic variables were computed from the position, speed and acceleration time series. Two-way ANOVA, Passing–Bablok regressions, and dynamic time warping analysis showed good to excellent agreement between Elite and DYSKIMOT, both at the qualitative level of the time series shape and at the quantitative level of peculiar kinematical events’ measured values. In conclusion, DYSKIMOT sensor is as relevant as a gold-standard system to assess kinematical features during fast head rotations in participants and patients, demonstrating its usefulness in both clinical practice and research environments.

Timed Up and Go and Six-Minute Walking Tests with Wearable Inertial Sensor: One Step Further for the Prediction of the Risk of Fall in Elderly Nursing Home People

“…Fallers were identified according to the fall records between the 6 months interval (t 1 and t 2 ). 20 [17][18][19][20][21][22][23][24][25][26][27] 17 [14][15][16][17][18][19][20][21][22][23] Age is indicated under the form mean ± standard deviation. Medications increasing the risk of fall: psychotrope, antiarrhythmic, diuretics [18].…”

“…During the six-minute walking test, participants were equipped with a homemade sensor collecting several kinematic data. The ultralow-cost sensor, called DYSKIMOT, was presented in a previous survey [14]. It is based on the Magnetic Angular Rate and Gravity (MARG) sensor LSM9DS1 (SparkFun), composed of a 3-axis accelerometer, gyrometer and magnetometer, plus a temperature sensor ( Figure 1A,B).…”

“…It is based on the Magnetic Angular Rate and Gravity (MARG) sensor LSM9DS1 (SparkFun), composed of a 3-axis accelerometer, gyrometer and magnetometer, plus a temperature sensor ( Figure 1A,B). It is light (10.44 g) and small enough (3 × 3 cm) to be worn by a patient without any disturbance ( Figure 1B [14], including a comparison between DYSKIMOT and a gold standard optoelectronic sensor. The sensitivity depends on the sensor and on the selected range; detailed information is given in the datasheet (https://www.st.com/en/mems-and-sensors/lsm9ds1.html).…”

“…For example, the gyrometer sensitivity is 8.75 × 10 −3 • /s/LSB at the range ±245 • /s, i.e., the range we use in the present study, and the accelerometer sensitivity is 0.322× mg/LSB at the range ±4× g. During the experiment, the DYSKIMOT was positioned in the lumbar region of the individual at the level of the L4 vertebra ( Figure 1C,D) in such a way that the sensor's cartesian frame matched with walking directions. [14], including a comparison between DYSKIMOT and a gold standard optoelectronic sensor. The sensitivity depends on the sensor and on the selected range; detailed information is given in the datasheet (https://www.st.com/en/mems-and-sensors/lsm9ds1.html).…”

“…Today, the availability of low-cost inertial sensors enables 3D measurement of acceleration and angular speed during human movements. In a recent study, we successfully used a homemade ultralow-cost wearable inertial sensor (DYSKIMOT) to capture the rotational movements of the head during a standardized test [14]. It is part of the DYSKIMOT project to show the relevance of the proposed sensor in a wide variety of clinically relevant situations, and the present study aims at extending the range of applications of the DYSKIMOT sensor.…”