The present invention concerns an electronic autoclave cycle sensor. Instruments used in surgery must be cleaned and sterilized after each use to eliminate microorganisms and viruses to prevent infection. While many sterilization methods are used, probably the most effective, lowest cost, quickest and most available method is application of steam in autoclave. However, an autoclave provides a hostile environment causing wear on surgical instruments that, over time, requires maintenance to avoid instrument failure.
Often, manufacturers set prescribed design goals for their instruments including warranting minimal number of autoclave cycles that the instrument was created to withstand. Accordingly, it is effective for the user understand how many autoclave cycles his or her instruments have undergone so that appropriate maintenance can be scheduled. Additionally, manufacturers of instruments are interested in knowing whether an instrument has been subjected using a sufficient number of autoclave cycles so as to render the instrument warranty void.
U.S. Pat. Hardly any. 3,450,489 to Fay discloses a sterilization control means containing a thermal responsive signal producing means enclosed within wrapped articles to be sanitized. The signal means produces and transmits a control signal from within the bundle which is required to control the sterilization operation to guarantee thorough sterilization for the wrapped articles. Fay fails to teach or suggest any means for counting the number of cycles to which an instrument is subjected nor does Fay teach or suggest any magnetic means to sense the number of autoclave cycles which an instrument may be subjected.
U.S. Pat. No. 3,568,627 to Sellenger et al. discloses a combined record card and sterilization indicator including a portion of the record that changes colors to indicate that sterilization has occurred. Sellenger et al. fail to instruct or suggest any magnetic means for counting the connected with autoclave cycles this agreement an instrument been recently subjected.
U.S. Pat. Not any. 4,235,842 to Thomas et al. discloses a temperature cycle indicating means for just about any sterilizer unit because of this designed to count the number of cycles of sterilization to which for the purpose of have been subjected. Thomas et al. fail to teach or suggest the utilization of magnetic means to do such function.
The present invention relates to an electric autoclave cycle sensing unit. The invention records the number of thermal cycles which an instrument been recently subjected in a steam autoclave. Since surgical instruments aren't supplied with power during autoclave sterilization, the inventive sensor is required to record the existence of a temperature change cycle passively, which event must be detectable through electrical reading and wherein the sensor should be electrically re-settable.
When a sterilization cycle has been completed, and the instrument is next energized in use, computer means comprising a microprocessor or microcontroller is used to read the sensor and record the occurrence of a sterilization pedal.
Information as towards the cumulative number of cycles through which your instrument has been subjected is input into a nonvolatile memory means such as, for example, an EEPROM. This info is suitably displayed on the display panel and/or is read out to a service computer on a serial data port or higher a modem with a factory service center.
When an unmagnetized ferromagnetic material is about in a magnetic field, such is actually the case each and every current passes any coil around the material, the flux density of insulating material rises. When the magnetic field taken out by stopping flow of the current, the flux density remains. This phenomenon is known as 'permanent magnetism'. In case the temperature of expand into all the is raised above a critical value known as 'Curie temperature', the exchange coupling suddenly disappears and materials becomes simply 'paramagnetic'. Paramagnetic materials don't exhibit the properties of permanent magnetism and their flux density is zero in the deficiency of an external sector. At temperatures near but below the Curie temperature, incredibly is only partial causing a permanent magnet to lose some of its retained flux denseness.
In the present invention, the sensor means employed uses either the Curie temperature or a temperature near but below the Curie temperature of a ferromagnetic material beginning with magnetizing the material and then, later, checking its flux density to assess if a thermal cycle has occurred. As should be understood for this above explanation, in case the magnetized material is exposed to a temperature at or near the Curie temperature, the magnetic flux density will fall and because it is can be sensed through energization associated with magnetic sensor. After sensing and recordation of an autoclave sterilization cycle, the magnetic material is re-magnetized so it really is ready to be familiar with sense the next sterilization cycle.
In the preferred embodiment, the magnetic material employed comes with a relatively low Curie temperature so it really is Curie temperature is reached or approached within the normal range of operating temperatures of an autoclave. An sort of such a material is Nd--Fe--B metal.
The present invention contemplates two possible sensor means for measuring the flux density of a magnetizable material. Within a first embodiment, a Hall effect sensor is used to directly measure the magnetic field strength of the magnetizable material so that the user can assess whether the magnetic field strength has been reduced as may be the case should totally be exposed to your near Curie or Curie temperature thereof. In a second embodiment, a sensor winding is previously sense the magnetic field strength of the magnetizable material which happens to be made in a mixture of shapes such as toroid shaped, similar to that used in magnetic core memory devices. The sensor winding is interconnected with an amplifier so that modifications to flux can be sensed.