`

`

Outline

Biological Analysis

Two models

Polychaeta

FORTH

Olygochaeta, Caterpillar

Modelling (for

locomotion)

SSSA

Control•How biological control in nematodes works

•Natural sensing

To be

discussed

today

Activity on tribology

Technological implementation

(torus)

Clamping

Hooks

Mechanical

Mucoadhesion

Proteic binding

Interfaces

The idea:

dehydrating mucus causes enhanced proteic binding between tissue and the “locomoting” device

The problem:

Can this effect be effectively exploited?

Adhesion study:

Using mucus as a natural glue

Adhesion study

Materials: 1. An explanted pig gut tissue was used

2. An adhesion surface was fabricated by using a medical gauze as a transpiring surface

Method:1. The normal force was measured before dehydration

2. Dehydration was produced by forced air convection at fixed pressure

3. The tangential force required for the detachment of the contact surface was measured as a function of the dehydration time.

Experimental investigation of protein binding

The measurement was performed by using the following device:

Compressed air is supplied through an axial inlet on top of the distributor and it outgoes through eight radial holes

In the lower part of the device, a medical gauze has been applied.

Experimental investigation of protein binding

The medical gauze has been stretched and fixed using an elastic ring Friction measurements

were made on the internal surface of a portion of pig colon, which is maintained moisturized to mimic physiological conditions.The device was pulled by a flexible wire which passes through a pulley suspended on a balls bearing.To the other end of the wire a tuned traction force was applied

Increasing adhesion by dehydrating mucus for protein binding

enhancement

The measurements were performed by maintaining a constant air flow of 10 cm3/sec through the device, for 4 time intervals: • 0 sec: the gut wall was perfectly wet (physiological conditions)• 90 sec: the gut walls began to be slightly dry• 180 sec: the gut walls was dry• 900 sec: the proteins contained in the gut mucus bonded to the gauze perfectly

The device weight (normal force on the friction surface) was 13.3 g (0.130 N) , while the frictional force generated by the pulley was estimated at about 0.15 g (1.5 10-3 N).

Protein binding increasing: experiments

Friction behaviour

050

100150200250300350400450500550600650700750800

0 100 200 300 400 500 600 700 800 900 1000

Time [sec]

Fri

cti

on

Co

eff

icie

nt

(x1

00

)

1° Measure 2° Measure 3° Measure Mean Value

1° Measure

2° Measure

3° Measure Mean Value

1 53.955 54.936 61.803 56.898

2 333.54 298.224 241.326 291.030

3 529.74 447.336 520.911 499.329

4 > 700 > 700 > 700 > 700

Friction Coefficient

1 0.436

2 2.230

3 3.826

4 > 5.363

Protein binding increasing: results

Protein binding enhancement: CONCLUSIONS

•Gauze or other fabrics are good surfaces for friction

•Adhesion enhancement by dehydration is effective

•Miniaturization:

•reduces the energy required for the dehydration of small

areas

• implies more technical difficulties, especially for

autonomous devices

•Future work:

•Better mimicking of physiological conditions (a

living tissue tends to recover its humidity level.

This does not happen with explanted tissues)