Temporomandibular joint. Temporomandibular joint. Temporomandibular problems. Engineering sensors in bio-applications

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1 Engineering sensors in bio-applications Mandibular movement Common Engineering Sensors in Bio-Applications Biofilm detection May 3 rd, 2007 Joaquim Mendes [jgabriel@fe.up.pt] Faculty of Engineering, University of Porto Porto, Portugal 0 Skin color Walk pressure and shear forces 1 Temporomandibular joint The temporomandibular joint, or TMJ, connects the lower jaw called the mandible, to the temporal bone at the side of the head. There are two temporomandibular joints, one on each side of the jaw. Since TMJ are flexible, the jaw can move smoothly up and down and side to side, allowing us to talk, chew and yawn. Muscles attached to, and surrounding the joint, control its position and movement. Temporomandibular joint When opening the mouth, the rounded ends of the lower jaw joint, called condyle, glide along the joint socket of the temporal bone The condyle slide back to their original position when we close our mouth 2 3 Why to measure the mandibular movement? Temporomandibular problems Study the chewing, the speaking, and the condyle movement Diagnosis of dysfunctions related with the articulation Occlusion interference Projection on the sagital plan Projection on the horizontal plan Headaches Bit problems Clicking sounds Locked jaws Aesthetics Wear of the teeth Ear pain Articulation pain Cervical pain Unequal development of the muscles 4 5

2 Mandibular kinematics Measuring systems based on optical sensors Mandibular kinematics Measuring systems based on ultrasound sensors Arcus Digma Mirror [ [ [Leader, 2002] [Kinuta, 2003] Reproducing the mandibular movements 6 7 Mandibular kinematics Measuring systems based on magnetic sensors Mandibular kinematics Measuring systems based on FGM sensors electrosonograph [ 8 [ 9 The idea GMR sensors Measuring system based on Giant Magneto Resistive sensors A magnet is glued inside the patient mouth, at the incisal point Facial arc Under a magnetic field, electrical resistance drops 10 to 15% [ 3D modelling of the facial arc, from Kavo, used as the main support structure for the new device Made using Inventor 10 11

3 Redesign of the auricular parts Design of the support for the sensors Project Old aspect New parts Support for the sensors Materialization of the support for the electromagnetic sensors done by rapid prototyping - stereolitography Stereolitography Stereolithography is the most widely used rapid prototyping technology Stereolithography builds plastic parts layer by layer by tracing a laser beam on the surface of a vat of liquid photopolymer This class of materials quickly solidifies wherever the laser beam strikes the surface of the liquid [ The self-adhesive property of the material causes the layers to bond to one another and eventually form a complete, 3D object Electronic unit Data acquisition device Power supply Characterization of the sensors response A 3D coordinate machine was used for the complete characterization of the sensors A neural network was developed in Matlab and trained with the acquired data 16 17

4 Neural Networks A radial basis neural network was built using Matlab and then integrated in the LabVIEW application Software application The software developed enables the visualization of the 3D movement, as well as, the projection on the plans. The software keeps also the records of the patients Final prototype Final remarks The prototype is able to follow the path of the incisive point in its 3D trajectory. However, the signal from the sensors is rather weak in a real situation, thus a higher resolution A/D should be used instead The software displays the important graphical data in 2D graphs, as well as, in a 3D user defined graph s orientation The device is comfortable for the patients and practical for dentists Team: Isa Santos Joaquim Mendes João Tavares Manuel Paulo The device is small and light weight It has a pleasant design and low cost (~400 ) Future work New sensors, more sensitive and with all three axes in a single chip Wireless communication (zigbee) New design to be able to fit on other commercial arcs Bibliography [Leader, 2002] - Leader JK, Boston JR, Debski RE, Rudy TE Mandibular kinematics represented by a non-orthogonal floating axis joint coordinate system, Elsevier, [Kinuta, 2003] - Kinuta S, Wakabayashi K, Sohmura T, Kojima T, Nagao M, Nakamura T, Takahashi J Simple system to record jaw movements by a home digital camcorder The International Journal of Prosthodontics, vol.16 no.5, p.p , Clinical validation 22 23

5 Biofilm growth Why do cells attach to surface? Biofilm growth is almost unavoidable hazard in water systems Water It is composed by Micro-organisms Extra cellular polymers Solid particles from the fluid River Treatment Plant Suspended particles Biofilms and other deposits Adhesion prevents cells from being washed out (removed) Cells protected them selves from external aggressions (e.g. biocides), it increases the chances of survival Biofilms are 150~3000x more resistant to Chlorine than the same microorganisms in suspension in Le chevalier 1988 Microbial metabolism may benefit from the interaction between different microorganisms 24 To concentrate nutrients from the flow 25 Problems arising from biofilm formation Increases the pressure drop Decreases the heat transfer Leads to the corrosion of pipes and duct Source of bacteria > lead to microbiological contamination, is a suitable environment for pathogenic microorganisms Biofilm Biofilm formation Monospecies 2D biofilm model ( Feast / Famine Periods Flow rate -> Shear forces Detachment Oxygen limitation Piezoelectric materials Discovered in 1880 (by Curie brothers) From the Greek piézein means squeeze Piezoelectric effect Ability of certain materials to produce and electrical charge proportional to the applied stress Converse effect When an electric field is applied to a piezo material, a proportional deformation will occur Main characteristics + High frequency response + Can be used either as sensor or as actuator + Do not generate magnetic fields (*) + High force capability + Compatible with vacuum applications - Small deformation (~0,1%) (*) specially important for medical applications 28 The idea By sensing the pipe vibration, one can evaluate the amount and type of deposits Metal sheet PZT layers Actuator Sensor 29

6 Sensing device Lab Setup Advantages: placed on the outer side of the pipe (non-intrusive) can be applied on different surface materials integrates the information of the deposit over a large area enables the identification of the type of deposit has low maintenance Flow cell Normalized Amplitude (V) Drinking water Time B 2 Biofilm T T B 3 F1 F 2 B 1 Team: Ana Pereira Joaquim Mendes Luis Melo flow Detailed view Data processing Accelerometer (Analog Devices) Full-scale range of ±1.7 g Bandwidth 0.5Hz to 2.5 khz Sensitivity 1V/g Weight <1gf Piezo bender (Piezomechanik) Supply voltage +/- 70V Capacitance 20 nf Displacement +/- 200 µm Blocking force 0.15 N Sensor Actuator 5 6 FFT analysis displacement 32 The computer generates the waveform through the data acquisition board (DAQ). The sensor response is measured by DAQ board and the wave parameters calculated 33 Vibration tests Laboratory of Optical Methods and Experimental Mechanics 34 Normalized Amplitude (V) Results Biofilm - Laminar Flow Biofilm - Turbulent Flow Silicate - Turbulent Flow Wet mass per area (mg/cm 2 ) Normalized Amplitude (V) Addition of disinfectant to a biofilm Time (days) 35

7 Industrial Application Skin color measurement Heat exchange plant Thank you for your attention 38