Summary of Research in the Centre The research of the Centre is divided into six main areas: Human Movement Functional Electrical Stimulation Microengineering Laboratories on a Chip Osseointegration Blood Flow and Vascular Grafts Other Research Human Movement Understanding the way in which the human body moves is fundamental in understanding the basis of many diseases and in assessing patients with abnormal walking (gait), such as stroke patients and amputees. The Centre for Biomedical Engineering boasts some of the best Gait Analysis facilities in Europe, based both at the University campus and at our Clinical Biomedical Engineering Centre [CBEC] in Queen Mary’s Hospital, London. Current projects are funded by the EPSRC and national/international government contracts. A novel design of Ground Reaction Force (GRF) walkway has been designed in-house and installed at Queen Mary’s Hospital, where it is used for clinical research and routine clinical assessment including the gait of amputees, patients recovering from stroke and children with cerebral palsy. We have also applied the same technology for assessing how shoe insoles affect the way people walk, and how custom-made insoles can be used to improve sports performance. Marker data with tracers Functional Electrical Stimulation When muscles and nerve pathways become damaged or have their function reduced as a result of disease, trauma or congenital condition, it is possible to restore some of the lost function by applying electrical stimulation to the remaining healthy tissue. Our work in functional electrical stimulation has allowed patients with such conditions as cerebral palsy, or “drop foot” as a result of stroke, to improve their mobility. Our stimulator systems are based on microcomputers worn by the patient, and use sophisticated gyroscope systems to allow the computer to determine the movements of the patients and respond accordingly. Current projects include stimulator and sensor development for gait assist following stroke and for children with cerebral palsy, and the application of stimulation to chronic denervated muscle. Project work is supported by Cerebra, EPSRC, INSPIRE, Remedi and Wandsworth Primary Care Trust. Setting up a stimulator for gait assist For a simple introduction to electrical stimulation click here - this is an edited version of some Web pages created by Miss Amanda Lamb, an MSc Student (1994-95). Microengineering The nervous system is the control network of the human body. Where permanent neurological damage has been sustained, or where a prosthesis has replaced an organ, there are advantages in connecting artificial, computer-controlled devices directly into the nervous system to replace or assist any remaining nerve functionality. In the long term, such work has the potential to allow computer-nerve interfaces for the control of artificial limbs or in the repair of damaged spinal cord. In order to build such interfaces, we have developed implantable microdevices (neuroprobes) for recording from the intact nervous system. These probes, much thinner than a human hair, contain electrodes that can record signals from individual nerve cells. Our work covers many aspects of neural interfacing, including signal processing, probe construction, and assessment of the body’s reaction to the probe materials. This advanced work is part of a long term programme supported by EPSRC and the UniS Foundation Fund. Sketch of a typical microprobe, and SEM of the tip of a 5 electrode microprobe Laboratories on a Chip Advanced microengineering techniques have allowed the miniaturisation of components normally found in a large laboratory, and reduced them to a size where a single device can perform a range of operations for clinical assessment, such as the identification of “rogue” cells (such as circulating tumour cells) in blood, or the assessment of drug action on the single-cell level, using novel electrostatic analysis (dielectrophoresis). Support from a number of sources (EPSRC, The Royal Society, DSTL, EU, Nuffield) has funded a broad range of projects. These include biosensors for bacteria detection and identification, analysis of the differences between drug-sensitive and drug-resistant cancer cells, rapid assessment of the action of drugs on cells and bacteria, rapid separation of cells using high-throughput electrostatic filters and enhanced sensors for the detection of airborne bacteria. The work has also extended to the theoretical study of nanotechnology in biomedicine. Electric field simulation of a cell trap Osseointegration Conventional prosthetic limb fitting is normally achieved by using a thermoplastic socket on the residual stump of the amputated limb. Problems with soft tissue damage, lack of limb control and constraints on limb fitting for difficult stumps may be overcome by using a new technique of implanting screw-like titanium devices into the bone, which protrude through the skin and to which an artificial leg is attached. This allows the body weight to be supported through the skeleton. The Centre for Biomedical Engineering, along with our clinical colleagues at Queen Mary’s Hospital, Roehampton, are part of an international collaborative effort to develop these implants, the project being led by Professor P-I Branemark of the Institute of Applied Biotechnology, Gothenburg. At UniS we are studying the optimisation of implant design, using experimental and computer simulation techniques, and the molecular interaction between titanium and bone to understand the mechanisms which make the bone-titanium interface so strong. This should influence the successful use of titanium implants for the direct attachment of artificial limbs. We are also devising new methods of studying the implantation process, and designing safety devices to protect the user – and the implant – from damage due to falls. Osseointegrated Lower Limb Blood Flow and Vascular Grafts When blood vessels fail, it is now possible to replace them with artificial blood vessels, or vascular grafts. These are usually constructed from woven polymer and bent to fit, but there is still much uncertainly about how they respond in the body (particularly in the first few days after implantation), and how blood flow – which is highly sensitive to pressure changes due to the material of the blood vessel – responds to the artificial material. Our work encompasses a range of approaches, such as experiments, computer simulations and analytical approaches, and includes established links with commercial vascular graft suppliers. Other Research As befits an active biomedical research centre with strong links to the health service, industry, charitable organisations and government departments, the Centre’s research portfolio extends beyond the themes outlined above. For example, a wide range of research activities are included in our Tissue Biomechanics theme, including studies of craniofacial structures using advanced 3D computer modelling, skin and overlying tissue properties of relevance to the design of surgical cosmeses and prostheses, heart valve harvesting and spinal disc prostheses. Other work includes novel measures for clinical assessment, wheelchair evaluation, and novel prosthetic limbs. Work in these areas is supported by the Department of Health, the Douglas Bader Foundation, EPSRC, the Norman Rowe Educational Trust and the Royal Society. d.ewins@surrey.ac.uk February 2004