Abstract: A vacuum control system controls the amount of time that pressure is applied to a breast and the amount of time no pressure is applied to the breast, independent of the vacuum level. The amount of time that pressure is applied to a breast and the amount of vacuum applied to the breast cups can be varied by the user. A disposable biological filter isolates the pump from the breast cups. The biological filter is packaged in a housing that has an O-ring push-in connector to connect the collection system to the pump. The vacuum applied to the breast cups is monitored. The control system maintains the vacuum at a level set by the user. A second higher level is used as a safety threshold. The control system shuts down the pump when this higher level is sensed. The breast cup is constructed to provide a controlled collapse when vacuum is applied to mimic the suckling of an infant.

Abstract: A membrane dome switch is disclosed which includes a tactile feel regulator shim to provide an enhanced and consistent tactile feedback in response to fingertip switch depression. The membrane dome switch includes a conductive domed spring member mounted in a sandwich or laminant array between an underlying circuit layer having a conductive circuit pattern thereon and an overlying shield layer. Fingertip pressure applied to the shield layer is effective to deform the spring member to momentarily close a circuit path on the circuit layer. The tactile feel shim is interposed between the spring member and the overlying shield layer, and functions to provide improved tactile feedback sensation during switch operation.