Patent Publication Number: US-9883776-B2

Title: Bathtub monitors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 14/097,408 filed Dec. 5, 2013, the entire contents of which are expressly incorporated herein in its entirety by reference. 
    
    
     BACKGROUND 
     The present disclosure contemplates that bathtub overflow alarms have been used to detect water flowing out of a bathtub. Such alarms, however, may not be useful for detecting some potentially unsafe conditions associated with bathtubs, such as drowning, due to their inability to detect conditions not associated with overflowing water. 
     SUMMARY 
     The present disclosure pertains to safety monitors, which may comprise alarms, and more particularly, to monitors and/or alarms for small bodies of water such as, for example, bathtubs, whirlpool tubs, medical spas, therapeutic spas, walk-in tubs, ‘kiddie’ pools, and the like. While the current alarm systems according to the current disclosure are configured to be used with any type of small body of water as described above, the embodiments of the current disclosure will be described for use with bathtubs for simplicity and exemplary purposes. For the purpose of the current claims, the term ‘tub’ shall include all such water-holding objects for occupancy by a person as described in this paragraph. 
     Some example embodiments according to at least some aspects of the present disclosure may comprise methods, apparatus, devices, and/or systems pertaining to bathtub monitors that may be configured to sense motion and/or absence of motion, such as motion associated with an occupant of a bathtub. Some example embodiments may be configured to provide local and/or remote alarm(s) upon detection of a potentially unsafe condition, such as an absence of motion of the occupant of a bathtub. 
     In some example embodiments according to at least some aspects of the present disclosure, a bathtub alarm system may comprise a sonar-based system that may be used, for example, to assist in preventing young children from drowning in a bathtub. The system may be configured to monitor the motion of a child in the bathtub using, for example and without limitation, ultrasound waves generated by a piezoelectric transducer, or by another motion sensor. 
     In some example embodiments according to at least some aspects of the present disclosure, a bathtub alarm system may comprise a pressure sensor, such as a piezo sensor, to sense movement (or lack of movement) in the tub by sensing pressure waves (or lack of pressure waves) within the tub. In more detailed embodiments, the bathtub alarm system may also include a temperature sensor, such as a thermistor, to sense the bathwater temperature so that the system may be configured to trigger an alarm if the bathwater exceeds a predetermined temperature, such as 100° F. 
     In some further example embodiments according to at least some aspects of the present disclosure a bathtub alarm system may comprise one or more accelerometers, which may be configured to detect change in gravitational force associated with the motion of an object in the body of water. In more detailed embodiments, the bathtub alarm system may also include a temperature sensor, such as a thermistor, to sense the bathwater temperature so that the system may be configured to trigger an alarm if the bathwater exceeds a predetermined temperature, such as 100° F. 
     In some example embodiments according to at least some aspects of the present disclosure, a bathtub alarm system may comprise a temperature sensor, exposed to water movement, to sense water movement (or lack of movement) in the tub by sensing voltage changes across the thermistor above an expected (or predetermined) level (such as comparing the voltage changes across a first thermistor exposed to water movement to voltage changes across a second shielded thermistor not exposed to water movement). The second shielded thermistor may also be utilized to sense the bathwater temperature so that the system may be configured to trigger an alarm if the bathwater exceeds a predetermined temperature, such as 100° F. 
     In some example embodiments, as long as sufficient motion is detected, the system may remain in a “monitor” mode. If no (or little) motion is detected for a predetermined amount of time, the system may initiate an alarm sequence. For example, the system may sound an audible alarm. If substantial motion resumes (e.g., for a preset amount of time), the system may return to the monitor mode. Alternatively, the alarm may be manually silenced by a user. 
     Some example embodiments according to at least some aspects of the present disclosure may comprise one or more ultrasound (U/S) transducers, which may be configured to transmit and/or create one or more standing waves in a body of water (e.g., a bathtub). The transducers may be configured to detect ultrasound modulated signals when the standing waves are disturbed by the motion of an object (e.g., a person) in the body of water. Some example embodiments according to at least some aspects of the present disclosure may comprise one or more pressure sensors, such as piezo sensors, to sense pressure changes across the sensor caused by movement within the body of water. Some example embodiments according to at least some aspects of the current disclosure may comprise one or more temperature sensors, such as thermistors, to sense changes in local temperature at the sensor due to movement within the body of water. 
     Some example embodiments according to at least some aspects of the present disclosure may include a central processing unit (e.g., a microprocessor) that may be configured to asses signals from the movement sensor(s). One or more algorithms may be utilized to analyze various parameters to discriminate between “motion” and “no motion” conditions in the bathtub. For example, an alarm signal may be issued based on the outputs of one or more algorithms configured to calculate the timing between different levels of motion strengths that may be associated with movement of a child in the bathtub. Sensors other than piezoelectric and/or thermistor, such as pressure, audio, infra-red, acceleration, floating and other mechanical sensors can also be used with minor modifications to the algorithms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram representation of an exemplary bathtub monitor system and environment according to the current disclosure; 
         FIG. 2  is a block diagram representation of an exemplary monitoring unit according to the current disclosure; 
         FIG. 3  is a block diagram representation of an exemplary remote unit according to the current disclosure; 
         FIG. 4  is an example plot of voltage over time according to an embodiment of the current disclosure; 
         FIG. 5  is a flow chart of an example method of operating a bathtub alarm according to at least some embodiments of the present disclosure; 
         FIG. 6  is a block diagram representation of another exemplary bathtub monitor system according to the current disclosure; 
         FIG. 7  is a block diagram representation of another exemplary bathtub monitor system according to the current disclosure; 
         FIG. 8  is a block diagram representation of another exemplary bathtub monitor system according to the current disclosure; 
         FIG. 9  is an example plot of voltage over time according to an embodiment of the current disclosure; and 
         FIG. 10  is a flow chart example method of operating a bathtub alarm according to at least some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of an example bathtub monitor system  10  according to at least some aspects of the present disclosure. Bathtub monitor system  10  may be used in connection with a small body of water, such as a bathtub  12 , which may contain water  14  and/or an occupant  16 . A monitor  18  may be disposed in, at, or near bathtub  12  and/or may include a sensor, such as a transducer  20 , operatively associated with water  14  and/or occupant  16 . As discussed below, transducer  20  may be configured to emit sound  22  into water  14  and/or may be configured to detect sound  24  in water  14  caused by movement of occupant  16 . In some example embodiments, emitted sound  22  may create a standing wave  25  in water  14 . In some example embodiments, transducer  20  may be in the form of a piezo sensor configured to sense movement (or lack of movement) in the tub by sensing pressure waves (or lack of pressure waves) within the bathtub  12 . In some example embodiments, transducer  20  may be in the form of a thermistor configured to sense changes in temperature at the thermistor that differs from expected temperature changes within the bathtub  12  (i.e., temperature changes attributable to movement in the tub rather than changes attributable to sensed or expected cooling of the bathwater, for example). Monitor  18  may be configured to emit a notification  26 , such as an audible alarm. Some example monitors  18  may be configured to communicate with a remote unit  28 , such as via a radio link  30 . Remote unit  28  may be configured to emit a notification  32 , such as an audible alarm. 
       FIG. 2  is a block diagram of an example monitor unit  100  according to at least some aspects of the present disclosure. Bathtub monitor  100  may include a power source (e.g., battery  102 ), a microprocessor  104 , and/or a transducer  106 . In some example embodiments, battery  102  may provide power to microprocessor  104  via a water-activated switch  108  and/or a voltage regulator  110 . Microprocessor  104  may transmit and/or receive sound in water  14  using transducer  106 , which, during use, may be at least partially immersed in water  14 . Microprocessor  104  may include an “on” indication (e.g., ON LED  112 ), a battery low indication (e.g., BAT LOW LED  114 ), and/or a standby button  116 . Upon detecting certain potentially unsafe conditions, microprocessor  104  may be configured to activate an alert device  118 , which may produce one or more visual, audible, tactile, and/or other notifications associated with the detected potentially unsafe condition. For example, alert device  118  may comprise a speaker, buzzer, light, and/or other similar notification devices. Some example embodiments may comprise a radio link  120  (e.g., a transmitter and/or a receiver), which may be configured to transmit notifications (e.g., notifications associated with potentially unsafe conditions) and/or other data (e.g., status messages) to one or more remote locations and/or to receive data (e.g., information and/or commands) from one or more remote locations. For example, commands may active and/or deactivate the bathtub alarm system. 
       FIG. 3  is a block diagram of an example remote unit  200  that may be used in connection with monitor unit  100 . Remote unit  200  may comprise a power source (e.g., battery  202 ) and/or a microprocessor  204 . In some example embodiments, battery  202  may provide power to microprocessor  204  via an on/off switch  206  and/or a voltage regulator  208 . Remote unit  200  may comprise an “on” indication (e.g., ON LED  210 ), a low battery indication (e.g., BAT LOW LED  212 ), and/or a standby button  214 . 
     Remote unit  200  may include a radio link  216  (e.g., a transmitter and/or a receiver) operatively coupled to microprocessor  204 . Radio link  216  may be configured to receive notifications (e.g., notifications associated with potentially unsafe conditions) and/or other data (e.g., status messages) from one or more remote locations and/or to transmit data (e.g., information and/or commands) to one or more remote locations. For example, radio link  216  of remote unit  200  may be configured to communicate with radio link  120  of monitor unit  100 . Upon receiving a notification associated with a potentially unsafe condition (e.g., via radio link  216 ), microprocessor  204  may be configured to activate an alert device  218 , which may produce one or more visual, audible, tactile, and/or other notifications associated with the detected potentially unsafe condition. 
     Some example embodiments according to at least some aspects of the present disclosure may comprise alarm logic programmed to perform methods of determining conditions of “motion” and “no motion” in bodies of water, such as bathtubs. For example, an ultrasound wave may be generated by a piezoelectric transducer (e.g., transducer  106 ) into the body of water (e.g., water  14  in bathtub  12 ) to create a standing wave (e.g., standing wave  25 ), which may act as a carrier wave and/or which may be of a frequency different from the frequency range of motion induced by a child in the water. 
     In some example embodiments according to the present disclosure, transducer  106  may be configured to detect sound waves associated with motion of the child. The sound waves associated with motion of the child may be filtered out from a carrier wave and/or may be converted to an electrical waveform. The amplitude of this waveform may then be averaged and/or amplified. A comparator may be used to compare this waveform and/or its timing with preset levels that may be associated with different levels of motion (e.g., “strengths”) within different periods of time. The microprocessor may then analyze these signals based on one or more algorithms and/or the microprocessor may issue commands that may result in caution beeps and/or full alarms. The microprocessor may also send commands to a wireless remote that may alert a person to the various activities of a child in the bathtub. 
     In some example embodiments according to at least some aspects of the present disclosure, a microprocessor and/or associated circuitry may be configured to average the electrical waveform associated with the motion of the child to produce an averaged voltage level. For example, the circuit may convert a Doppler frequency (e.g., about 25 Hz) to a voltage ramp that changes level at about a 110 mV per second rate. The microprocessor may sample the ramp voltage about every 200 ms. As long as the sampled voltage exceeds a minimum reference level (e.g., 0.25 V), the monitor may stay in monitor mode. Whenever the sampled voltage drops below the minimum reference level (e.g., 0.25 V), the monitor may start a low level alarm sequence that may escalate to a full alarm, such as over a period of seconds. At any time the sampled voltage exceeds the minimum reference level (e.g., 0.25 V) the alarm sequence may halt and the monitor may return to monitor mode. 
     The microprocessor and/or associated circuitry may compare the averaged voltage level to a predetermined threshold (e.g., 0.25 V). If the averaged voltage level remains at or above the predetermined threshold, then the microprocessor may assume that there is sufficient motion of the child to remain in monitor mode and not sound an alarm. If the averaged voltage level drops below the predetermined threshold volts and remains below threshold for a predetermined period (e.g., 200 ms), the alarm sequence may be initiated. The alarm sequence may start with a beep at an initial volume and or rate (e.g., low volume and about one beep per second). If motion in the bathtub is not detected, the alarm sequence may continue to an escalated alarm, such as a full-volume, continuous beep. In some example embodiments, the alarm escalation may occur in steps over a period of time, such as a gradual increase in volume and rate over a one minute period in 200 ms steps. If the changing voltage rises above the threshold for a predetermined period of time (e.g., above 0.25 volts for 200 ms), the alarm sequence may stop and the system may return to monitor mode. 
       FIG. 4  is an example plot of voltage over time. As discussed above, when the sampled voltage is below a minimum threshold voltage (e.g., 0.25 V), an example embodiment may be in an alarm mode. When the sampled voltage is above a minimum threshold, (e.g., 0.25 V) an example embodiment may be in a monitor mode. 
       FIG. 5  is a flow chart of an example method  300  of operating a bathtub alarm according to at least some embodiments of the present disclosure. Method  300  may include an operation  302 , which may include comparing a level of sound in water in a bathtub associated with movement of an occupant of the bathtub with a threshold level. Operation  302  may be followed by operation  304 , which may include initiating an alarm sequence if the level of the sound in the water in the bathtub that is associated with the movement of the occupant is below the threshold. 
       FIG. 6  is a block diagram of another example monitor unit  500  according to at least some aspects of the present disclosure. Bathtub monitor  500  may include a power source (e.g., battery  502 ), a microprocessor  504 , and/or a transducer in the form of a piezo sensor  506 . In some example embodiments, battery  502  may provide power to microprocessor  504  via a water-activated switch and/or a voltage regulator  510 . Microprocessor  504  may receive sound in water  14  using piezo sensor  506 , which, during use, may be at least partially immersed in water  14 . Microprocessor may be operatively coupled to a water sensor  520 , for sensing that the monitor unit  500  is immersed in water  14 , for example; and may be operatively coupled to a thermistor  522  for sensing the temperature of the water  14 . Microprocessor  504  may include an “on” indication and/or a “battery low” indication through LEDs  512 . Microprocessor may also be operatively coupled to a standby button  516 . Upon detecting certain potentially unsafe conditions, microprocessor  504  may be configured to activate an alert device  518 , which may produce one or more visual, audible, tactile, and/or other notifications associated with the detected potentially unsafe condition. For example, alert device  518  may comprise a speaker, buzzer, light, and/or other similar notification devices. Some example embodiments may comprise a radio link  521  (e.g., a transmitter and/or a receiver), which may be configured to transmit notifications (e.g., notifications associated with potentially unsafe conditions) and/or other data (e.g., status messages) to one or more remote units  200  and/or to receive data (e.g., information and/or commands) from one or more remote unites  200 . For example, commands may active and/or deactivate the bathtub alarm system. 
     The embodiment of  FIG. 6  may operate as follows. A parent may secure the monitor unit  500  to the tub  12  wall via attached suction cups (not shown), for example. As the tub  12  is filled with water  14 , the water sensor  520  will detect the water and upon such detection, the processor  504  will turn the monitor  500  on, or activate the monitoring functionalities. When the tub  12  is drained, the sensor  520  may detect the absence of water and cause the processor  504  to turn the monitor  500  off. When the monitor  500  is activated, there may be a delay cycle programmed in before the alarm becomes active (armed). In the meantime, the parent may place the child in the tub  12  (or the child may already be in the tub as the water is filling the tub). Once the monitor  500  arms, activity from the child  16  within the tub may be detected by the piezo sensor  506 . As long as the child remains active, the alarm  518  will not sound. If the processor  504  determines that the child&#39;s activity has stopped based upon signals from the piezo sensor  506 , the processor  504  may be configured to trigger the audio alarm  518  and/or transmit information via radio transmitter  521  to the remote unit  200 , which may in response emit an audio alert  218 . 
     As the child plays in the bathtub  12 , the child&#39;s movements generate small pressure waves. In a detailed exemplary embodiment, as these pressure waves move the piezo sensor  506 , the movements generate a series of charges at the input of the charge amplifier  524 . The high impedance of the charge amplifier  524  allows these charges to produce a series of pulses. The sensor&#39;s capacitance and the high impedance feedback resistor of the charge amplifier  524 , create a high pass filter, with a low frequency cut off of 0.59 Hz. The low pass filter  526  has a high frequency cutoff of 3.28 Hz, creating a band pass filter, with a range of 0.59 to 3.28 Hz. The band pass filter allows the processor  504  to look at frequencies generated by the child&#39;s movement, and block frequencies not generated by the child. The processor  504  monitors these pulses as movements. When the processor  504  observes a pulse (movement) it resets a 60-second timer. If the processor  504  does not see a pulse/movement within the 60-second time window, it starts an alarm sequence. The alarm sequence is a sequence of beeps (emitted by the audio alert  518 , for example) and quiets that increase in volume and frequency as the alarm continues. The alarm is designed to alert the parent with increasing urgency while not scaring the child with a sudden very loud alarm. Depending upon the level of urgency, movement from the child can resent the alarm sequence and return the processor  504  to monitor mode. By pushing the standby button  516 , the processor  504  will be in stand-by mode for 60 seconds (monitor  500  is on, but not detecting movement). Pushing the stand-by button  516  during an alarm sequence will reset the alarm sequence and place the monitor  500  in stand-by mode. 
     In the current embodiment, the monitor  500  may also serve as a thermometer and temperature alarm. A precision thermistor  522  changes resistance according to the temperature of the bathwater  14 . The processor  504  monitors this resistance, and displays the associated temperature on an LCD display  528 . Further, if the processor  504  senses that a temperature above a predetermined threshold, such as 100° F., the processor  504  may trigger a high temperature alarm to be emitted by the audio alert  518  and/or by the remote unit&#39;s  200  audio alert  218 . A jumper may be provided to allow the temperature monitor to switch between Fahrenheit and Centigrade measurements. 
       FIG. 7  is a block diagram of another example monitor unit  600  according to at least some aspects of the present disclosure. With the embodiment of  FIG. 7 , the piezo transducer is replaced with another thermistor  530  to sense movement within the bathwater  14 . With this embodiment, there are two thermistors in the tub monitor  600 , the shielded or fixed thermistor  522  and the exposed or variable thermistor  530 . The shielded thermistor  522  is in the bathwater  14  but shielded from water movement caused by the child taking the bath. The exposed thermistor  530  will be in the bathwater and exposed to water movement. Both thermistors are supplied power by a constant current generator. When the shielded thermistor  522  is active and in the bathwater  14 , the only change in resistance will be due to a change in water temperature; and that change will be minimal in many cases as the bathwater will be cooling slowly. When the exposed thermistor  530  is in the bathwater  14  and the constant current generator is on at 5 mA, the thermistor&#39;s  530  resistance will reach a stable value which is a balance of the self-heating characteristic and the heat dissipation of the bath water. When the water around the exposed thermistor  530  is moving, from a child in the bathtub  12 , this balance is upset and the voltage across the thermistor changes. The processor  504  will be configured to monitor the voltage change across each thermistor to determine if the exposed thermistor  530  is changing more than the shielded thermistor  522 , therefore detecting child&#39;s movement within the tub  12 . 
     In some example embodiments according to at least some aspects of the present disclosure, one or more sensors other than sound transducers, piezo transducers or thermistor transducers may be used to sense motion of the occupant of the bathtub. For example, alternative sensors include, without limitation, alternate pressure sensors, infra-red sensors, accelerometers, floating sensors, and other similar sensors known in the art. Generally, alternative sensors, such as pressure transducers and moving float sensors, may produce outputs associated with child movement in the tub in the frequency range of about 10 to about 500 Hz. Outputs of amplification and/or filtering circuitry associated with such sensors may be averaged and/or evaluated in generally the same manner as the sound transducer embodiment discussed above. 
     The present disclosure contemplates that a “false alarm” may occur if the occupant of a bathtub remains substantially still for a period of time. As discussed above, some example embodiments may be configured with an alarm sequence comprising an initial local audible alarm at a relatively low level, which may induce some movement by the occupant of the bathtub. If the induced movement is sufficient to reset the alarm, then then the alarm sequence may be terminated at that point without having escalated to a full alarm and/or without sending a notification to a remote unit. In some example embodiments, initial, low-level alarm notifications may be provided to remote units. 
     Some example embodiments according to at least some aspects of the present disclosure may be integrated with baby monitor technology, such as to provide audio and/or video monitoring in connection with the motion-based alarms described herein. 
     In some example embodiments according to at least some aspects of the present disclosure, a standing wave produced by a transducer may have a frequency of about 10 kHz to about 1 MHz. In some example embodiments, a standing wave may have a frequency of about 40 kHz to about 100 kHz. 
     Some example embodiments according to at least some aspects of the present disclosure may be configured to detect sound associated with movement of an occupant of a body of water of about 10 Hz to about 500 Hz. Some example embodiments may be configured to detect sound associated with movement of an occupant of a body of water of about 10 Hz to about 30 Hz. Some example embodiments may be configured to detect sound associated with movement of an occupant of a body of water of about 25 Hz. 
     As used herein, “no motion” may refer to conditions in which there may be some motion, but the motion may be below a threshold of detectability. Also, as used herein, “no motion” may refer to conditions in which there may be some detectable motion, but the detected motion may be less than a threshold for consideration as sufficient motion to prevent an alarm. 
     In some example embodiments according to the present disclosure, accelerometer  531  may be configured to detect gravitational force associated with motion of the child. The gravitational forces associated with motion of the child may be sampled for strength, amplitude, or frequency of change in gravitational force and compared to a predetermined value or may compare this frequency and/or its timing with preset levels that may be associated with different levels of motion (e.g., “strengths”) within different periods of time. The microprocessor may then analyze these signals based on one or more algorithms and/or the microprocessor may issue commands that may result in caution beeps and/or full alarms. The microprocessor may also send commands to a wireless remote that may alert a person to the various activities of a child in the bathtub. 
     In some example embodiments according to at least some aspects of the present disclosure, a microprocessor and/or associated circuitry may be configured to average the gravitational forces associated with the motion of the child to produce an averaged gravitational force level. For example, the circuit may convert gravitational force to gs. The microprocessor may sample gravitational force about every 200 ms. As long as the sampled gravitational force exceeds a minimum reference level (e.g., 0.3 g), the monitor may stay in monitor mode. Whenever the sampled gravitational force drops below the minimum reference level (e.g., 0.3 g), the monitor may start a low level alarm sequence that may escalate to a full alarm, such as over a period of seconds. At any time the sampled gravitational force exceeds the minimum reference level (e.g., 0.3 g) the alarm sequence may halt and the monitor may return to monitor mode. 
     The microprocessor and/or associated circuitry may compare the averaged gravitational force to a predetermined threshold (e.g., 0.3 g). If the averaged gravitational force remains at or above the predetermined threshold, then the microprocessor may assume that there is sufficient motion of the child to remain in monitor mode and not sound an alarm. If the averaged gravitational force drops below the predetermined threshold gs and remains below threshold for a predetermined period (e.g., 200 ms), the alarm sequence may be initiated. The alarm sequence may start with a beep at an initial volume and or rate (e.g., low volume and about one beep per second). If motion in the bathtub is not detected, the alarm sequence may continue to an escalated alarm, such as a full-volume, continuous beep. In some example embodiments, the alarm escalation may occur in steps over a period of time, such as a gradual increase in volume and rate over a one minute period in 200 ms steps. If the changing gravitational force rises above the threshold for a predetermined period of time (e.g., above 0.3 gs for 200 ms), the alarm sequence may stop and the system may return to monitor mode. 
       FIG. 8  is a block diagram of another example monitor unit  700  according to at least some aspects of the present disclosure. Bathtub monitor  700  may include a power source (e.g., battery  502 ), a microprocessor  504 , and a accelerometer  531 . In some example embodiments, battery  502  may provide power to microprocessor  504  via a water-activated switch and/or a voltage regulator  510 . Microprocessor  504  receive gravitational force from movement in water  14  using accelerometer  531 , which, during use, may be floating in water  14 . Microprocessor may be operatively coupled to a water sensor  520 , for sensing that the monitor unit  500  is immersed in water  14 , for example; and may be operatively coupled to a thermistor  522  for sensing the temperature of the water  14 . Microprocessor  504  may include an “on” indication and/or a “battery low” indication through LEDs  512 . Microprocessor may also be operatively coupled to a standby button  516 . Upon detecting certain potentially unsafe conditions, microprocessor  504  may be configured to activate an alert device  518 , which may produce one or more visual, audible, tactile, and/or other notifications associated with the detected potentially unsafe condition. For example, alert device  518  may comprise a speaker, buzzer, light, and/or other similar notification devices. Some example embodiments may comprise a radio link  520  (e.g., a transmitter and/or a receiver), which may be configured to transmit notifications (e.g., notifications associated with potentially unsafe conditions) and/or other data (e.g., status messages) to one or more remote units  200  and/or to receive data (e.g., information and/or commands) from one or more remote unites  200 . For example, commands may active and/or deactivate the bathtub alarm system. 
     The embodiment of  FIG. 8  may operate as follows. A parent may place the monitor unit  700  in the tub  12  for example. As the tub  12  is filled with water  14 , the water sensor  520  will detect the water and upon such detection, the processor  504  will turn the monitor  700  on, or activate the monitoring functionalities. When the tub  12  is drained, the sensor  520  may detect the absence of water and cause the processor  504  to turn the monitor  700  off. When the monitor  700  is activated, there may be a delay cycle programmed in before the alarm becomes active (armed). In the meantime, the parent may place the child in the tub  12  (or the child may already be in the tub as the water is filling the tub). Once the monitor  700  arms, activity from the child  16  within the tub may be detected by the accelerometer  531 . As long as the child remains active, the alarm  518  will not sound. If the processor  504  determines that the child&#39;s activity has stopped based upon signals from the accelerometer, the processor  504  may be configured to trigger the audio alarm  518  and/or transmit information via radio transmitter  520  to the remote unit  200 , which may in response emit an audio alert  218 . 
     As the child plays in the bathtub  12 , the child&#39;s movements generate small motion waves. In a detailed exemplary embodiment, as these motion waves move the accelerometer, the movements generate a series of signals to the microprocessor  504 . The processor  504  monitors these signals as movements. When the processor  504  observes a signal (movement) it resets a 60-second timer. If the processor  504  does not see a signal/movement within the 60-second time window, it starts an alarm sequence. The alarm sequence is a sequence of beeps (emitted by the audio alert  518 , for example) and quiets that increase in volume and frequency as the alarm continues. The alarm is designed to alert the parent with increasing urgency while not scaring the child with a sudden very loud alarm. Depending upon the level of urgency, movement from the child can resent the alarm sequence and return the processor  504  to monitor mode. By pushing the standby button  516 , the processor  504  will be in stand-by mode for 60 seconds (monitor  700  is on, but not detecting movement). Pushing the stand-by button  516  during an alarm sequence will reset the alarm sequence and place the monitor  700  in stand-by mode. 
     In the current embodiment, the monitor  700  may also serve as a thermometer and temperature alarm. A precision thermistor  522  changes resistance according to the temperature of the bathwater  14 . The processor  504  monitors this resistance, and displays the associated temperature on an LCD display  528 . Further, if the processor  504  senses that a temperature above a predetermined threshold, such as 100° F., the processor  504  may trigger a high temperature alarm to be emitted by the audio alert  518  and/or by the remote unit&#39;s  200  audio alert  218 . A jumper may be provided to allow the temperature monitor to switch between Fahrenheit and Centigrade measurements. 
       FIG. 9  is an example plot of gravitational force over time. As discussed above, when the sampled gravitational force is below a minimum threshold (e.g., 0.3 gs), an example embodiment may be in an alarm mode. When the sampled gravitational force is above a minimum threshold, (e.g., 0.3 gs) an example embodiment may be in a monitor mode. 
       FIG. 10  is a flow chart of an example method  700  of operating a bathtub alarm according to at least some embodiments of the present disclosure. Method  700  may include an operation  702 , which may include comparing a level of gravitational force from water movement in a bathtub associated with movement of an occupant of the bathtub with a threshold level. Operation  702  may be followed by operation  704 , which may include initiating an alarm sequence if the level of the gravitational force from water movement in the bathtub that is associated with the movement of the occupant is below the threshold. 
     While example embodiments have been set forth above for the purpose of disclosure, modifications of the disclosed embodiments as well as other embodiments thereof may occur to those skilled in the art. Accordingly, it is to be understood that the disclosure is not limited to the above precise embodiments and that changes may be made without departing from the scope. Likewise, it is to be understood that it is not necessary to meet any or all of the stated advantages or objects disclosed herein to fall within the scope of the disclosure, since inherent and/or unforeseen advantages may exist even though they may not have been explicitly discussed herein.