Measurement of the force applied by a finger-tip on an object using Magnetic Resonance Imaging.

SID: 200643372, iMBE, School of Medical Engineering, University of Leeds.

References : 1. Earls, J.P. ‘Digital MRI: The Fingers and Toes.’2. Fagiani, R., Massi, F., Chatelet, E., Berthier, Y. and Akay, A. ‘Tactile perception by friction induced vibrations.’ Tribology International 44; 2011; 1100-1110.3. http://www.melbourneradiology.com.au/mri-gallery/mri-fingers-and-toes.html.4. The, J. and Whiteley, G. ‘MRI of soft tissue masses of the hand and wrist.’ The British Journal of Radiology 80; 2007; 47-63.5. Zaitsev, M., Dold, C., Sakas, G., Henning, J. and Speck, O. ‘Magnetic resonance imaging of freely moving objects: Perspective real-time motion correction using and external optical motion tracking system.’ NeuroImage 31; 2006; 1038-

1050.

1. Introduction 2. Principle

3. Procedure

4. Expected Results

6. Conclusion

• Quality of a packaging material can be detected by surveying it with one’s finger-tip.

• The emotions generated by the roughness or smoothness of the material gives an idea about the material’s quality.

• Additional information about the quality of the product present inside can also be gathered.

• The optimum force required to scan the surface still remains unknown.

• The aim of this poster is to present a possible method to detect the forces applied by a finger-tip on a packaging material using MRI.

Fig 1. Commodities that are generally scanned by finger-tips.

http://pollynoble.com/2010/09/cheesey-sweet-potato-crisps-recipe/

Fig 2. A shopper using her finger-tips to sense the quality of a product.

http://www.telegraph.co.uk/news/uknews/2609556/Supermarket-price-comparison-Middle-classes-face-their-Ocado-moment.html

• Below the digital pulp of the finger lies various sensory receptors such as Meissner’s and Pacinian corpuscles (fig 3).

• Activation of these pressure and touch receptors, by the friction induced vibrations, provides information about the coarseness of the object the finger is touching (fig 4).

• The curvature of the digital pulp region, at the point of contact, gives an idea about the force applied by the finger (fig 5).

Fig 3. Schematic representation of different parts of a human finger.

http://visual.merriam-webster.com/human-being/sense-organs/touch/finger.php

Fig 4. Different sensory receptors present under the finger-tip skin.

http://candacewalraven.wikispaces.com/K.++Sensory+Organs

Fig 5. The action-reaction forces acting on the finger and producing a

curved digital pulp.http://

www.imaginis.com/sports-medicine/orthopedic-mr-imaging-new-levels-of-diagnostic-information-on-sports-injuries

.http://myplaceofpeace.blogspot.co.uk/2009/11/empty-shampoo-bottle.html

• Along with visionary perception, the sensation of touch is very important in judging the quality of a packaging material.

• Magnetic Resonance Imaging is a non-invasive method of imaging and hence no adverse effects are produced on the finger.

• Force measurement can be performed by MRI.• The knowledge of forces applied by shoppers enables companies to

make better product packaging that are not only soothing to the eye but also good to touch.

5. Discussion• The finger will be in motion and hence signal to noise ratio will be low.• Packaging materials having magnetic properties can not be used for the

test.• Placing the experimental set-up inside the open-extremity MRI scanner

will be challenging. Using a C-scan MRI device will be more beneficial than an E-scan MRI machine.

• Contrast agents and external optical motion tracking cameras might be needed.

• Step 1: Attach the packaging material on the top of the aluminium bar and prepare the experimental set-up as shown in fig 6.

Fig 6. The experimental set-up and the movement of the finger.

• Step 2: Place the experimental set-up inside the open-extremity MRI scanner. The finger is moved once as shown in fig 6.

• The required field strength is about 1.5 Tesla and the RF coil can be a quadrature wrist coil.

Fig 7. The open extremity MRI scanners that can be used for the test are (a) E-scanner and (b) C-scanner.

(a) http://www.alakamedical.com/itemdetail.cfm?ProductID=332. (b) http://www.mghradrounds.org/index.php?src=gendocs&link=2009_may.

a b

• Step 3: The lateral MRI image of the finger is then examined and the extent of concavity at the tip of the finger (shown by a red box in fig 8) is calculated.

• The deeper the digital pulp is pushed inside the higher is the force applied by the finger.

Fig 8. The area of interest in the MRI image of the finger.http://www.imaginis.com/sports-medicine/orthopedic-mr-imaging-new-levels-of-diagnostic-information-on-sports-injuries

.

• Step 4: Calculating the force applied by the finger depending on the concavity of the finger-tip. This can be done with the help of a coding using a mathematical software like MATLAB.

• Fast spin echo (FSE) should be used while capturing the images as this will decrease the computational errors.

Shampoo

Concavity

Force Applied

• Force-displacement curve. • Maximum force to be applied for the perfect perception.

• Improved quality of the packaging material.

• A standardised experimental method can be generated using the results.

• This will make the procedure laboratory independent and set the benchmark for the maximum force applied.Force Applied by the finger (N).

Displacement of the Digital

Pulp.Fig 9. The Force vs

Displacement Graph.

Better quality

Soothing perception

Higher SalesLarger

Revenue

Force Perception

Confused.None.

Perfect.