RESNA 26th International Annual Confence

Technology & Disability: Research, Design, Practice & Policy

June 19 to June 23, 2003
Atlanta, Georgia


T. D. Adlam, C. C. Gibbs, R. D. Orpwood,
Bath Institute of Medical Engineering,
University of Bath, UK.


The short-term memory loss associated with dementia makes completion of complex tasks difficult. Two systems have been designed that monitor cookers, and baths and hand basins. The systems are able to intervene in the event of a dangerous or unwanted situation and make that situation safe or call for help from a local or remote third party. Evaluation of these systems is being carried out in the UK and Ireland.


People with dementia experience profound short-term memory loss, but retain long-term memories for much of their illness. This means that established patterns of behaviour and familiar environments can be navigated with little assistance. However if a person is moved from a familiar environment to one that is unknown, considerable confusion and consequential disability can result. The loss of short-term memory often makes it very difficult or impossible for the person with dementia to learn a new environment and the behaviours associated with that environment.

Enabling people with dementia to stay in their own homes for as long as possible rather than moving them to residential care allows them greater independence and quality of life as they are able to carry out tasks of daily living for themselves.


A survey (1) carried out for this project showed that concern about cooker safety was one of the most frequent reasons for people being moved into residential care. The objective of this work is to design systems that will monitor a person's use of the bath, wash basin and cooker and intervene, making them safe should the user leave them in a condition likely to cause harm.

1) Bath and Basin Monitor

People with dementia turn on taps to run a bath or fill a wash basin and then leave the room for some reason, forgetting that the water is running. This can result in floods and costly damage to their home and other property if they live in a block of flats. If this situation occurs often, a person with dementia will be moved into residential care.

The basin and bath monitor system is designed to monitor the water level in the bath or wash basin, intervening to prevent the water from overflowing into the room if the taps are left on.

2) Cooker Monitor

People with dementia leave cookers switched on without igniting the gas, creating an explosion risk; or leave a pan on the cooker that can boil dry or overheat.

Often cookers in the home are old; however changing them to a more modern design that auto-ignites is not a suitable solution as the user interface is changed and becomes unusable to the person with dementia. There is a need for a system that can be retrofitted to existing cookers, that a person with dementia will be able to use as before, but that will intervene in potentially dangerous situations.


Several principles have been adhered to as closely as possible during the design of these systems.

The purpose of the monitoring system is to allow the user increased independence and quality of life; therefore the monitoring system should not reduce the user's ability to use the appliance it is fitted to.

It is important that the user interface remains unchanged so that a person with dementia who is unable to learn a new interface is still able to use the device.


This figure shows a schematic diagram of the bath monitoring system. The diagram shows a central controller linked to a two water level sensors, a bath hand wheel, a solenoid valve, a messaging device and a communications system. There is a bath shown that is part filled with water to which the two level sensors attached. The bath is being filled by water from the bath handwheel. The water flow is controlled by the valve.  

This system comprises two modified bath or basin taps, two solenoid-operated proportional valves, messaging and communications devices and a controller.

Figure 1 shows the system with one tap and valve though in practice two are fitted.

The valve is not directly connected to the handwheel, which is just a control input. If the user operates the handwheel, it appears to have the same effect as turning a tap on or off as normal. The controller operates the valve as the handwheel is turned. An electromagnetic brake fitted to the handwheel shaft ensures that the fully on and fully off positions feel as they should.

The messaging device is used to inform the user of interventions that the monitoring system has made and to remind the user of actions that need to be taken. It uses, at present, a conventional radio that has been modified to play a pre-recorded message on demand using a radio link. The messaging system is independent of the radio receiving equipment and works even if the radio is turned off.

System Operation Scenario

The user turns on the taps, is distracted and leaves the bathroom, forgetting that the taps are running and filling the bath.

The Bath Monitor detects that the water level has reached the normal depth for a bath and initiates the reminder to play a message such as "Don't forget you've left the bath running". A timer is started that will trigger an intervention if the user does not turn off the water.

If this reminder is ignored and the timer expires, the system intervenes, turning off the water supply and applying the brakes to the taps so that they feel `turned off'. Another message is played that says "Your bath's ready, I've turned the taps off".

If the user wishes to add more water to their bath after this intervention, they are able to do so as the taps are still functional in the usual way.

A second depth sensor disables the taps before the water level reaches the top of the bath.


The Cooker Monitor (Figure 2) consists of a controller, three sensors (gas, smoke and heat), four cooker knobs, a GSM mobile phone module and a power-off gas isolation valve.

The system monitors the hob and its environment looking for potentially dangerous situations such as a pan overheating or the presence of unburned gas. In the event of such a situation occurring, the controller will intervene by turning off the gas supply using the cooker knobs. If the dangerous situation does not abate after intervention, the monitor isolates the cooker from the gas supply and uses the GSM module to send an SMS message to a third party who will call and ensure that appropriate action, if any, is taken. The system also isolates the cooker if it detects a system fault or if there is a power cut.

This figure shows a schematic diagram of the cooker monitoring system. The diagram shows a controller with inputs from three sensors that detect heat, gas and smoke. There are outputs from the controller to the cooker knobs, an isolation valve and a GSM mobile phone module. There is a link from the isolation valve to the hob showing that the valve cuts of the gas supply when operated. There is a link from the GSM module to a remote carer. This is dotted to show that it is a wireless link.  


Bath & Basin Monitor

The Bath Monitor has proved to be reliable in use by people without dementia except for an interference problem that caused the taps to turn on unexpectedly. This problem was solved in a subsequent prototype. The system will be installed in the home of a person with dementia for long-term evaluation.

Cooker Monitor

The Cooker Monitor is part of the ENABLE project, which is evaluating equipment for people with dementia in Europe. Eight units will be installed in the UK and eight in Ireland for evaluation with people with dementia. Evaluations with naïve users have shown that the system functions correctly.


These two monitoring systems have the potential to considerably improve the quality of life of people with dementia as well as reducing the cost of care through allowing people to stay in their own homes for longer. Further work into human/machine interfaces for people with dementia is in progress to determine effective means of communicating information from machines to people with dementia. The `radio' interface used in these systems is a first attempt for evaluation.


  1. Jepson, J., Orpwood, R., (2000). The use of smart home technology in dementia care, Proceedings of Ann. Conf. of College of Occupational Therapists, Keele University, UK.


The Gloucester Smart House is funded by the Engineering and Physical Sciences Research Council, under the EQUAL programme.

The European evaluations of the cooker monitor are funded by the European Commission as part of the ENABLE project.

Timothy Adlam
Bath Institute of Medical Engineering
Royal United Hospital
Bath. UK. BA1 3NG
Tel: +44 1225 824 103
Fax: +44 1225 824 111

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