Biomimetics and Biomimicry in Engineering

Posts Tagged ‘porous materials’

Removing mass with maths

In Comment on 2017/11/14 at 3:02 pm

We are creating lightweight materials by removing mass from where it is not needed and adding it to places subjected to high loads and strains. It is Drawing with Maths

“[The Universe] is written in the language of mathematics, and its characters are triangles, circles and other geometrical figures, without which it is humanly impossible to understand a single word of it” —Galileo Galilei, The Controversy on the Comets, 1618


Engineered foams for wheelchair seating

In Publications on 2017/11/08 at 10:39 am

We have published the results arising from our studies on open cell polymeric foams that can be tailored so that they support those who are bed bound or wheelchair users providing them with general well being and alleviating pressure points.

Avoiding pressure points, managing sores and permitting air permeability are the three main design specifications that clinicians aim to when choosing a cushion. In addition to that, a functional cushion, such as those who support lateral movements (e.g. leaning sideways to grab a glass of water and be helped to return to your initial position without compromising one’s stability) and protect from vibration and impacts (e.g. dropping off a curb), are the focus of our research project.

The Multifunctional Materials Lab and clinicians from the NHS have studied how we can help their clinician colleagues understand cushion performance and therefore aid them with the prescription of these to patients and users.

The results from our study have been published in the Medical Engineering and Physics Journal and in the Assistive Technology Journal .

The International Standard that regulates developments in this topic is the ISO16840-2:2007, which is currently under revision. We are hoping our work to inform their work and assist in their revisions for the replacement ISO 16840-2.



Porosity and pore size effect on the properties of sintered Ti35Nb4Sn alloy scaffolds and their suitability for tissue engineering applications

In Publications on 2017/11/03 at 11:04 am

Our most recent results on the importance of tailoring porosity engineered materials for cell regeneration are to be published in the Journal of Alloys and Compounds.

Porous scaffolds manufactured via powder metallurgy and sintering were designed for their structure (i.e. pore size and porosity) and mechanical properties (stiffness, strength) to be controlled and tailored to mimic those of human bone. The scaffolds were realised to fulfill three main objectives:

(i) to obtain values of stiffness and strength similar to those of trabecular (or spongy) bone, with a view of exploiting these as bone grafts that permit cell regeneration,

(ii) to establish a relationship between stiffness, strength and density that allows tailoring for mass customisation to suit patient’s needs; and

(iii) to assess alloy cytotoxicity and biocompatibility via in vitro studies.

The results obtained using a very low stiffness alloy (Ti35Nb4Sn) further lowered with the introduction of nominal porosity (30–70%) with pores in the ranges 180–300 μm and 300–500 μm showed compatibility for anatomical locations typically subjected to implantation and bone grafting (femoral head and proximal tibia). The regression fitting parameters for the linear and power law regressions were similar to those found for bone specimens, confirming a structure favourable to capillary network formation. Biological tests confirmed non-cytotoxicity of the alloy.

Scaffolds of porosity nominal 50%vol and pore range 300–500 μm performed best in the adhesion and propagation assays due to a good balance between surface area and pore cavity volume.

Graphical abstract for

Study on bio-mechanical properties of porosity scaffolds tailored for cell regeneration,

A pre-view of the article appears on Journal of Alloys and Compounds, Volume 731, 15 January 2018, Pages 189-199,


Manufacturing Functionality: from SFF to truly SFF

In Seminars and Keynotes on 2016/04/05 at 8:13 pm

Solid Free Form (SFF) fabrication, also known as Rapid prototyping (RP) or Layered Manufacturing (LM), creates arbitrary 3D shapes directly from Computer-Aided Design (CAD) data. It has been around for two decades now. From its early age it demonstrated tremendous advantages for the Computer-Aided Manufacturing (CAM) industry compared to traditional manufacturing methods such as CNC machining or casting. The venues for exploration appeared endless until users started to hit a ceiling; the name ‘rapid’ became almost ironic because the layering process is a very slow one, the palette of materials to handle is limited and the advertised label ‘net-shape’ is ‘near-shape’ – on a lucky day-. We are now over the hype of SFF, RP and LM but still have needs to create heterogeneous structures that have intrinsic multifunctionality. The Multifunctional Materials Manufacturing Lab in Loughborough University works on new manufacturing methods that allows a truly free form fabrication and the engineering of composition and structure for the creation of materials that are smart, responsive to their environment and possess synergistic properties that enhance their behaviour. These types of high performance materials offer great promise in fields such as bioengineering and transport (i.e. automotive and aerospace).

Venue: Department of Physics, Universitá degli Studi di Milano, Aula Consiglio. Italy



In Funding on 2016/02/24 at 2:58 am

Lightweight materials are the next pit-stop in the challenge of reducing mass, curbing emissions and improving fuel economy in the low carbon vehicles of tomorrow.

UK’s ambitious commitment to decarbonisation of the transport industry by 2050 is going to require a creative approach. Current reductions have been gained by improvements in engine performance but these gains are diminishing. If we were to go 100% electric, we still need to produce the electricity, so the footprint is not necessarily diminished as much as it could appear. To meet the carbon emissions target we need to reduce vehicle mass. For example, a car the size of a Ford Focus would need to reduce mass by about 300kg (from ~1200kg to ~900kg).  The car industry needs to find a way to manufacture lightweights without adding production cost in the shorter term.

Loughborough University and Far UK Ltd, a Nottingham-based innovative low-volume tailored vehicle designer and manufacturer, have joined forces to explore the concept of novel and engineered structures, multifunctional materials bespoke for their mechanical properties, and manufactured in a cost-benefit and continuous fashion using Sonication technology that allows on-demand tailoring of porosity. This exciting research program has just secured co-funding from the UK’s innovation agency, Innovate UK.

This programme of research presents a new avenue for high value manufacturing and helps support the UK knowledge base, economy and jobs.


We have been in the press here and here

Is DIY a western thing?

In Info on 2015/09/11 at 6:18 pm

Changxi Huang has been working on the bamboo hut project as part of his MSc project. His work has focused on the optimisation of the procedure for assembling the hut and looking for ways of best presenting the assembly instructions to those who can’t read instructions or have no previous knowledge on building huts.

He ran experiments with participants from different walks of life and, most importantly, from western and far east countries. One of the main points of discussion of his dissertation is based on his observations on the approach that western nationals have towards do-it-yourself products versus that of Far East countries citizens. In countries like China, assembling a product (a table or a chest of drawers) is left to those who perform that job for a living. On the contrary, the B&Q-isation or the IKEA-ising of western countries has made our exposure to self-assembly furniture and products an activity of our everyday life. Could this have an effect on our cognitive ability to understand instructions and our dexterity to carry out such assemblies?

Huang observing one of the tests in our study

Huang observing one of the tests in our study

Huang has successfully finished his MSc course and is going back to China for a most deserved rest. Well done, Huang!

MSc exhibition on 9th Sept (Loughborough University) and Farewell (or a ‘see you soon’):


The Future Engineer podcast engineer

In Seminars and Keynotes on 2015/02/10 at 11:23 am

STEM XX 016 episode is on the importance of multidisciplinary engineering, the power of positive thinking and biomimetics – learning from nature to solve our technical problems.

If you have ~30min to spare, have a listen and please leave comments below and tell me what you think. Thanks!

You can listen to it here and download it here.

Mathematical Modelling of the use of Ultrasound to Tailor Polymers

In Info, Seminars and Keynotes on 2015/01/27 at 12:13 pm

Materials whose internal porosity can be tailored during the manufacturing process could be of use in a wide range of applications such as bone scaffolds (to help new bone grow from stem cells).  A recent method for achieving such a manufacturing process involves the acoustic irradiation of a reacting polymer foam which then results in a final sample with a graded porosity.  This talk will present the first mathematical model of this process. The polymerisation process is complex involving, for example, bubble dynamics, evolving rheology, two phases, reaction kinetics, and gas diffusion.  In addition, the model has to include the effects of the irradiating ultrasound.  The model I will present treats the evolving fluid as a multimode Oldroyd B system and will focus on a single moving bubble boundary using a Lagrangian frame of reference.  After looking at the role that inertia has on the dynamics of the system, a multi-bubble model is constructed that generates a heterogeneous bubble size distribution shaped by the ultrasonic standing wave pattern.

My colleague Dr Tony Mulholland, from the Department of Mathematics and Statistics, University of Strathclyde, will present this remarkable piece of work on the 27th January 2015 at 1pm in venue: S.1.73 (Materials Department, Loughborough University). Join us if you can.

Making sense of standardisation

In Publications on 2013/11/18 at 12:27 am

Standardisation is that useful process that allows us engineers to share a common ‘plane of reference’ on which to base our conversations. It is useful to know that a material (say, a slab of titanium) has the same mechanical properties when it is measured in Loughborough, Sydney, Lima or Granada.

But sometimes standardisation goes too far on the other extreme. The over-translation from observation to technical definitions might turn an ISO norm into a document that is no longer useful for practical purposes. This is particularly risky when ISO norms attempt to tabulate and measure in ‘softer’ areas such as healthcare and rehabilitation.

In a piece of work recently published here, my colleagues from the NHS Scotland SMART Centre and we have restated some practical insight to an ISO norm that guides the characterisation of wheelchair cushions for a better guidance to prescription by clinicians.

Our work has been well received by the practising community and we look forward to continue working with them.

Ref: Hollington J., Hillman S.J., Torres-Sanchez C., Boeckx J., Crossan N., “ISO 16840-2:2007 load deflection and hysteresis measurements for a sample of wheelchair seating cushions”, Medical Engineering & Physics, in press. DOI:10.1016/j.medengphy.2013.10.010 

Learning from natural ‘sandwich’ structures

In Info on 2013/07/16 at 10:28 am
porcupine quill

porcupine quill

The porcupine quill is a quite interesting material. A pretty large shear modulus, flexible in 3-pt bending tests, but very stiff in the longitudinal direction, which serves well as a defensive weapon.

It is surprisingly lightweight, so the first thought is for a sandwich structure of different materials, but what type of structure?

The photos below show images of a longitudinal slice of a quill under the optical microscope. As expected, a soft core (cellular-foam like) and a denser ‘skin’.

Optical micrsocope images: transversal section and several magnifications

Optical microscope images: transverse section and longitudinal at several magnifications

As it commonly happens, the interesting story starts when you get to see beyond what the human eye can. At higher magnifications, the ‘skin’ shows a complex structure, with layers of material oriented so they form another ‘skin’ structure within the ‘skin’ itself, with a core oriented vertically (in these photos) and the skin running horizontally. (The big black vertical scars could be scratches at the time of polishing, though)

Transverse sections at different magnifications

Transverse sections at different magnifications

This multiscale ‘skin’ is a good solution for providing stiff properties but not at the expense of heavy, dense materials.

Special thanks to Andy Sandaver, who recently retired from the Wolfson School and we already miss his exceptional technical skills. And my gratitude to Edinburgh Zoo, where the samples were collected.