Sip-and-puff or sip 'n' puff (SNP) is

assistive technology Assistive technology (AT) is a term for assistive, adaptive, and rehabilitative devices for Disability, people with disabilities and the elderly. Disabled people often have difficulty performing activities of daily living (ADLs) independently, ...

used to send signals to a device using

air pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The Standard atmosphere (unit), standard atmosphere (symbol: atm) is a unit of pressure defined as , whi ...

by "sipping" (inhaling) or "puffing" (exhaling) on a straw, tube or "wand." It is primarily used by people who do not have the use of their hands. It is commonly used to control a

motorized wheelchair A motorized wheelchair, powerchair, electric wheelchair, or electric-powered wheelchair (EPW) is a wheelchair that is propelled by means of an electric motor (usually using differential steering) rather than human power, manual power. Motorized ...

by quadriplegics with very high injury to their

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

or people with

ALS Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States—Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and low ...

.{{cite web, url=http://atwiki.assistivetech.net/index.php/Alternative_wheelchair_control , title=Alternative wheelchair control - ATWiki , publisher=Atwiki.assistivetech.net , date= , accessdate=2011-11-04

Calibration and setup

Devices that use SNP technology require specific amounts of air pressure to be "sipped" or "puffed" by the user. These amounts of pressure are typically denoted as a hard sip/hard puff or soft sip/soft puff, however other terminologies might exist. Note that the words "hard" and "soft" are relative to the user and depend on their breathing abilities. Typically, air pressure levels pertaining to hard sips/puffs and soft sips/puffs are set through an initial

calibration In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...

of the

pressure sensor Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressur ...

completed before the user starts to use their SNP device. With the assistance of an aid or technician, the user will program the SNP device to recognize their body's ability to produce hard sips/puffs and soft sips/puffs. Once this calibration process is complete, the SNP device will only recognize the user specific sips and puffs that have been saved into the SNP device.

Motorized wheelchair control

Typical applications of Sip-and-Puff devices are for control of a

. Control typically consists of four different inputs from the user. An initial hard puff will enable the wheelchair to move forward, while a hard sip will stop the wheelchair. Conversely, an initial hard sip will enable the wheelchair to move backward, while a hard puff will stop the wheelchair. A continuous soft sip or soft puff will enable the wheelchair to move left or right respectively depending on how long the user blows into the tube, straw or "wand".

Computer input device

The mouth-controlled input provide users a simple and effective way to control

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

movement. Movement and operation of this

joystick A joystick, sometimes called a flight stick, is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Also known as the control column, it is the principal control devic ...

is similar to that of a mouth stick. Mouse button clicking is accomplished with the help of sips or puffs function of the joystick. A sip-and-puff input device combined with

computer accessibility Computer accessibility refers to the accessibility of a computer system to all people, regardless of disability type or severity of impairment. The term ''accessibility'' is most often used in reference to specialized hardware or software, or a co ...

software means many keyboard-accessible programs can be used with this device.

References

External links

What is a Sip-N-Puff device?
* http://www.theallineed.com/engineering/06082931.htm * http://www.wheelchairnet.org/WCN_ProdServ/Products/adldev.html * http://atwiki.assistivetech.net/index.php/Alternative_wheelchair_control Assistive technology