Design Inputs – Adjustable Lower Limb Socket (ALLS)

The device must adjust to accommodate volume changes of the residual limb while used.
- Justification: To allow for swelling and contraction of the residual limb without discomfort or further injury.
- Specification: The device adjusts over a range of -1.43% to +3.19% of the residual limb’s volume
The device must be able to support the user’s weight during daily activities.
- Justification: To allow mobility and safety for user during ambulation.
- Specification 1: The device will support a max of 10.15 psi in every region.
The device must be able to be easily donned and doffed.
- Justification: To allow easy access and be user friendly
- Specification 1: The device will be donned in under 5 minutes.
- Specification 2: The device will be doffed in under 1 minute and 40 seconds.
The device must be compatible with prosthetic attachments from popular manufacturers.
- Justification: To allow for the attachment of transfemoral prosthetic devices from the most universally used manufacturers.
- Specification: The adapter on the distal end must be compatible with prosthetic devices that represent 50% of the market share.
The device must be cleanable.
- Justification: To maintain proper hygiene.
- Specification: The material of the device will be able to be cleaned with unspecialized cleaning products.
The device must measure interface pressure of the inside of the socket.
- Justification: Pressure increases due to volume change in the residual limb can induce skin injury.
- Specification 1: Sensors will measure interface pressure in range of 0-3.6 psi.
- Specification 2: Sensors will be placed: two on each panel at 3.5in and 8in from the bottom of the socket.
The device must notify the user when pressure increases can cause injury.
- Justification: To let the user know when to loosen the adjustment mechanism to prevent further skin injury
- Specification 1: Device must notify user when measured average pressure is greater than or equal to 2.22 psi for a 15minute time period.
- Specification 2: Notification method TBD; specifications will follow
The device must be powered for a clinically relevant period of time.
- Justification: To ensure that the device can sense the pressure change without needing to recharge/replace the batteries throughout the day
- Specification 1: The device must stay powered for at least 9 hrs
- Specification 2: The battery powering the device must have an average amp-hour lifespan of XX amp-hours
The device conforms to electrical safety standards
- Justification: To ensure the device is safe for close body interaction and protects against electrical hazards
- Specification 1: Leakage current must be no more than 100 µA