Biomedical Engineering

Robotic technology in surgical therapy has demonstrated accurate and consistent tool trajectories in contrast with manual intervention. It has been a great achievement to deploy these machines in the operating theatre in close proximity to patients and staff and now commercial systems are available.

Our research focuses on controlling tool-point interaction precisely in small tissue targets. Hand supported devices are within this scope. Unique autonomous sensor controlled processes discriminate different tool working conditions/ tissues and the state of the tool-point/ tissue interaction and behaviour. This is used to enhance control by the surgeon in real-time relative to tissue position and produces consistent results. The devices require little set-up time and other infrastructure in the operating room. This approach offers great benefit as small tissue targets are often attempted working through difficult access.

The solutions investigated are generic.

Often there is a need to identify tissue types and behaviour, and to control the tool-point cutting force with respect to tissue interfaces and membranes in real time. The robotic surgical micro-drill discriminates the different states and behaviour moving the tool autonomously relative to tissue interfaces without penetration.

In cochleostomy, the precise and consistent results enable removal of bone tissue and preservation of the underlying endosteal membrane. Trauma to the hearing organ is reduced, there is greater opportunity to retain residual hearing. Sterility is maintained and debris can be removed before insertion of the electrode.

This approach to penetration has many applications in surgery.

In this research, steerable digits are produced as tool points to aid palpation and navigation in lumen. To navigate complex paths within soft tissue lumen requires an instrument that is steerable at the tip and sensitive to touch.

The novel sensor system enables tactile information feedback. This retrieves information on motion and is able to discriminate the path followed, the nature of contact and tissue characteristics such as stiffness. Few sensing elements are applied in this approach leading to a pragmatic and robust construction.

Applications are endoscopic and laparoscopic tools; catheters; and implantable devices for therapy and diagnosis.

The research is investigating the merits of the sensing approach over a range of sizes from that of the human digit down to sub millimetre in diameter. This solution is suitable for implantable devices, surgical and diagnostic tools.

Heart failure rate is reaching epidemic levels in the western world. The Cardiac Assist Devices team is investigating the production of a micro-axial flow pump to assist the failing heart. In addition a new generation of Intra aortic Balloon pumps (IABP) are being explored. This type of pump is the most widely used and currently response and efficacy of IABP are sensitive to posture. The research is considering how to maintain performance of the balloon, irrespective of posture.

Whilst IABP has been extensively used clinically decades and its benefits demonstrated through numerous clinical trials for over 3 decades, the detailed scientific knowledge of its effects is not well understood.

We are interested in studying the solid mechanics of the balloon and also the associated fluid mechanics caused by the inflation and deflation of the balloon. An interesting point that is of our interest is the effect of patient’s posture on the performance of the balloon.

When the balloon is at an angle to the horizontal, such as when the patient is laying in the semi-recumbent position, there will be a hydrostatic pressure difference between the two ends of the balloon; bottom end falling under a higher pressure, Pbottom=Ptop + rgh where r is blood density, g is gravity acceleration (9.81 m/s²) and h is the latitude difference between the two ends of the balloon. This hydrostatic pressure difference between the two ends of the balloon forces the filling of the balloon to start from the top, and this pattern of inflation displaces more blood volume away from the ascending aorta, which is opposite to what is desired, and raises a wider question about the ratio between flow upstream and downstream from the balloon during inflation, which we term “balloon efficiency”. In order to force the filling of the balloon to start from the bottom to the top the possibility of changing the shape of the balloon requires to be explored. The cylindrical shape of the intra aortic balloon has not been changed for the past 25 years!

Clinical Importance: Most patients using IABP in intensive care units are usually laying in the semi-recumbent position for various clinical and social reasons. Thus, optimising the shape of the balloon to maintain – if not increase - patients’ benefit at various postures is certainly of clinical interest.

Smart sensing systems that automatically output information discriminating types of patient pathology can support the busy practice of medicine. Many patient monitoring processes for metrics and screening can be accomplished by using the sensing surface described in this research. Mechanically simple, robust, cost effective and efficient to use are the advantageous properties of the sensing system.

Rather than outputting data, smart sensing instruments output information to enable efficient and consistent diagnosis and monitoring in critical care or screening processes. A sensing system may track the state of a patient and alert critical changes, and can take the form of a bed, chair or floor. In other applications, smart sensing systems can empower patients to monitor themselves, and be integrated into daily living, as a walking aid, a mat, or in sport.

 Reliable long-term medical implants such as drug dosage forms, tissue engineering scaffolds and biosensors drastically reduce the burden on healthcare system, while improving longevity and quality of life.

As drug dosage forms, tailored biomaterials deliver a bioactive agent at the target (implant) site for desired time periods and are resorbed following the intended function. As tissue engineering scaffolds they help regenerate damaged or lost tissue.

Miniature biosensors implanted in the body require substantially smaller sample volumes than traditional lab testing devices. They provide near instantaneous and maximal information for better patient management decisions, improved patient outcomes and reduced overall cost of care. There are also opportunities for feedback-controlled therapy and remote patient management.

Technologies already being developed are making life easier for patients by reducing the number of visits to a GP surgery or emergency room, and by minimising life threatening complications.

Two products that aim to reduce the impact of continence problems and increase user confidence and self esteem.

The Tackling ageing continence through theory tools and technology (TACT3) study.

Fear of pad leakage and urine odour have been cited as two of the most common concerns among continence pad wearers.
Working with a consortium of other UK Universities BIB staff have developed Smart underwear with integral sensors and a detachable signalling system that can detect a leak from a continence pad into the underwear. The alerting signal warns the wearer, allowing them to manage this problem before the urine spreads to outer clothes or furniture.

The other assistive product that BIB staff have recently been developing as part of the same project is a colour change odour detector that is able to detect the low levels of ammonia present in stale urine. The device reassures pad users by alerting them to the odour of stale urine before it can be detected by the human nose.

More information about the project can be found on the TACT3 website.

FES Rowing After SCI: Health, Sport and Recreation

Paralysis following spinal cord injury (SCI) results in reduced muscle mass that can be involved in physical activity. This can lead to secondary conditions including; obesity, cardiovascular disease and diabetes. Physical exercise in excess of 2000 kcal/week and the minimum oxygen consumption of 21 ml/kg/min is required. This will lower the relative risk of coronary heart disease and significantly improve blood lipids fractions. Many persons with SCI have difficulty achieving these levels and are often limited by fatigue of the arms. Electrical stimulation can be used to increase the amount of metabolically active muscle. The physical exercise that simultaneously involves both the upper body and the stimulated lower limbs can exceed the required oxygen consumption and weekly exercise volume.

We have demonstrated that computer controlled multichannel electrical stimulation of the leg muscles and voluntary arm motion can facilitate rowing on an adapted ergometer and on-water. The pulling actions involved in rowing may also be therapeutic for those with overuse shoulder pain as a result of chronic wheelchair propulsion.

In the development of hearing technologies the understanding of cochlear fluid dynamics is key. Hearing implants and hearing aids should operate with minimal power levels. Surgical procedure using new techniques and tools should be devised to minimise disturbances within the hearing organ to preserve patient residual hearing as far as possible.

A new technique has been developed by the research team for measuring disturbance amplitude within the cochlea. Unlike other techniques, this method does not invade the closed fluid volume in order to install pressure transducers. As a result, disturbances measurements by the new method are considered more accurate. Now it is possible to contrast the nature of disturbances within the cochlea and to identify the relative merits of different surgical tools and techniques.

Research on fundamental bio-fluid mechanics is investigating respiratory air flow and blood flow in arteries. The work on assessment of arterial plaques, and the development of cardiac assist devices is important in healthcare.

The principal objective in the assessment of arterial plaque by using non-invasive imaging modalities such as ultrasound and MRI is to evaluate the risk of plaque rupture and consequent stroke. An analytical approach to quantify risk of rupture is being explored as a tool to assess options in patient treatment.

Carotid plaque specimen photo and 3D ultrasound image

Stress distribution showing a region of stress concentration upstream of the plaque

A mathematic modelling system can simulate tumour growth from a few cancer cells to a mature solid tumour. The associated tumour angiogenesis and blood perfusion are based on certain laws.

In the simulation, tumour growth changes the local distributions of vascular endothelial growth factors which influences endothelial cell migration and angiogenesis. At the same time, the newly formed microvessels change local oxygen supply to influence tumour growth.

The simulation enables the study of the dynamic response of the tumour to the change in local environment. It can be used to evaluate tumour therapy, drug delivery and treatment stratagies.

3D tumour microvasculature

2D tumour and associated microvasulature, 24 days old

Two products that aim to reduce the impact of continence problems and increase user confidence and self esteem.

The Tackling ageing continence through theory tools and technology (TACT3) study.

Fear of pad leakage and urine odour have been cited as two of the most common concerns among continence pad wearers.
Working with a consortium of other UK Universities BIB staff have developed Smart underwear with integral sensors and a detachable signalling system that can detect a leak from a continence pad into the underwear. The alerting signal warns the wearer, allowing them to manage this problem before the urine spreads to outer clothes or furniture.

The other assistive product that BIB staff have recently been developing as part of the same project is a colour change odour detector that is able to detect the low levels of ammonia present in stale urine. The device reassures pad users by alerting them to the odour of stale urine before it can be detected by the human nose.

More information about the project can be found on the TACT3 website.

FES Rowing After SCI: Health, Sport and Recreation

Paralysis following spinal cord injury (SCI) results in reduced muscle mass that can be involved in physical activity. This can lead to secondary conditions including; obesity, cardiovascular disease and diabetes. Physical exercise in excess of 2000 kcal/week and the minimum oxygen consumption of 21 ml/kg/min is required. This will lower the relative risk of coronary heart disease and significantly improve blood lipids fractions. Many persons with SCI have difficulty achieving these levels and are often limited by fatigue of the arms. Electrical stimulation can be used to increase the amount of metabolically active muscle. The physical exercise that simultaneously involves both the upper body and the stimulated lower limbs can exceed the required oxygen consumption and weekly exercise volume.

We have demonstrated that computer controlled multichannel electrical stimulation of the leg muscles and voluntary arm motion can facilitate rowing on an adapted ergometer and on-water. The pulling actions involved in rowing may also be therapeutic for those with overuse shoulder pain as a result of chronic wheelchair propulsion.

Tools for Living, Hardware, Software and Concept Cars

The Tools for Living Team, working under the direction of Emeritus Professor Heinz Wolff, is concerned with care and support systems for older people, who wish to continue living in their own homes. This requires a revision of current care policy, which is unaffordable, especially in the present economic climate.

A scheme called Care4Care where younger people perform duties useful to the community including care and support for relations and neighbours; thereby earning “credits” on an account which would guarantee them care and support when they need it. Research and development on the rules governing the operation and the organisational framework including setting up of a pilot is in progress.

The Companion is a computer system based around a graphical user interface designed to enable older users to interact with ICT services. Running on a laptop or all-in-one computer the system does not use a mouse or keyboard, the only input device being a barcode reader; current models also have a touch-screen. All on-screen output is accompanied by computer generated speech. The Companion has been used successfully by 100+ users for shopping in the Bristol area for the last three years.

The Liberty is a concept car based on a 1962 BMW Bubble Car chassis and body, modified for electric propulsion. It is very short, having a single door at the front and can be parked with the door opening directly onto the pavement. One of the seats is electrically powered and will propel the occupant to a position from which they can step directly onto the pavement. It will be used as a platform to investigate the cognitive environment most suitable for the aged driver.

More information about the Care 4 Care project can be found here.