Posted on Monday, June 6th, 2011
Originally published in MDT: Medical Design Technology (www.mdtmag.com).
Practicing Sound Medicine
Audible devices are playing an increasingly critical role in modern healthcare. Unfortunately, device manufacturers may not be aware of all the options available to them when it comes to sound components. This article reviews a variety of characteristics and important features companies should keep in mind when electing to add an audible aspect to their finished medical device.
By Ely Zofan
There’s an alarming trend occurring throughout the healthcare marketplace, and it is providing numerous growth opportunities for the instrumentation manufacturers that can fulfill demand for products that provide—among other things—clear, reliable audible signals for a cost-conscious audience.
The use of sounding devices in medical instrumentation is ubiquitous to say the least. One can visit any wing or department of a health center and hear a range of electronic tones as this form of electronics does what it does best—provide audible data to operators in exchange for a response or action. Yet as the technology advances and becomes even more integral to patient care, there is a steady increase in the demand for devices that can generate specific tones to help medical technicians and staff distinguish one priority from another. And like so many other electronics, these devices are migrating towards smaller packages and footprints.
Multi-Sensory Solutions
Research shows that people absorb data more effectively through multiple senses. The human eye alone can only focus on one visual stimulus, with peripheral vision used for scanning. Faced with multiple, often unpredictable, visual alerts, doctors, nurses, and med techs may quickly reach a point of visual overload, particularly in acute care settings including emergency rooms, surgical suites, and maternity departments.
Auditory senses are generally more complex, enabling the human brain to process greater amounts of unrelated data simultaneously. Combining visual and auditory senses has been an essential part of the medical profession, especially in critical care where immediate response to warnings is essential to saving lives. Moreover, the integration of audio technology serves to increase personnel productivity and efficiency without compromising quality of care. Harnessing human auditory cognition requires a clear hierarchy of auditory signals, as all sounds are not of equal importance. The introduction of new sounds or tones requires careful consideration based upon the level of medical or diagnostic emergency. Selecting the right audible device involves cost and performance considerations such as size and weight, type of sound required, variability of sound, loudness and frequency, expected service life, lead free (RoHS) compliance, and other key variables.
This group shotof sounding devices available through Challenge Electronics represents several specifically mentioned in the article: CE-C80, CSPT, and CSET series.
Medical Alarms and Annunciators
Audible devices such as speakers, alarms, transducers, and microphones are in all types of bench top instruments and hand-held devices. These components offer high performance, high quality audible characteristics for communications and signaling. Microphones and speakers are often used to communicate data between patient and nurses, or between doctors and nurses. In some instances, speakers are used to signal codes to alert hospital staff without causing undue concern for the patient.
Portable or Hand-Held Devices
We live in a mobile world, and as a result, portable and hand-held medical devices are commonplace. During the full cycle of a surgical patient’s stay in a hospital, he might encounter dozens of data collection points that involve scanning, monitoring, and verification for a variety of purposes—from basic metabolic readings to bedside medication dispensing or patient identification verification. Key performance parameters include size, weight, and energy efficiency, as comfort and convenience are primary considerations. However, as portable devices become increasingly miniaturized, quality and reliability can become major concerns.
Hand-held devices typically use a sound transducer to generate audio signals. These devices allow the manufacturer to conserve space, power, and cost. Piezoelectric transducers are typically used for low power and higher operating voltage applications (5 to 30 VDC). As a rule, the smaller the size of the piezoelectric transducer, the higher the resonant frequency and the lower the sound level. A 15-mm diameter piezoelectric diaphragm is typically 4,000 to 6,000 Hz, while a 25-mm diameter and larger diaphragm can produce 3,000 Hz and lower frequencies. Magnetic transducers are typically used in low voltage power sources, as well as for lower sound frequency applications, including pagers, wireless monitors, patient identification systems, and other portable devices.
These transducers are typically mounted on printed circuit boards and are driven by the electronics circuit provided by the equipment manufacturer. Use of a transducer gives the OEM the flexibility of producing multiple sounds. For example, the CSPT23A09-4.0F piezoelectric transducer measures 23 X 23 X 10.8 mm, with 1 to 25 Vpp operating voltage, 4,000 ±500 Hz resonant frequency, and 100 dB output at 10 cm. The CSET8.5A3.6-16-2.7F magnetic transducer measures 8.5 X 8.5 X 4.0 mm, with 2 to 4 V op operating voltage, 2731 Hz resonant frequency, and 88 dB output at 10 cm.
Many portable and hand-held medical devices now rely on miniature SMD and PCB microphones and speakers. There are SMD speakers such as the CSMS15A, which measures just 20 X 20 X 4.3 mm, with 8 ohms impedance, and 0.3 W rated power. This low footprint speaker saves space on the printed circuit board while delivering about 89 dB of sound at 0.1 meter at 0.3 watts. Typical applications for SMD speakers include portable and wearable devices utilized in surgical suites, specialty labs, critical care facilities, home healthcare, and nursing homes.
Alarms for Stationery Instruments
Many stationary systems and portable devices currently in use were built with lower cost alarms and sounding devices. These systems, while economical, have often proven less effective because of lower life expectancy or an inability to perform up to specifications. Poorly designed alarms may not turn on, or the sound levels may vary depending upon what is located in front of the sound port.
Some medical instruments routinely go through a cleaning cycle to reduce bacteria growth. If the alarms are not hermetically sealed, washing solution could leak into the alarm and short the alarm, causing severe damage to the instrument. Alarms with stainless steel terminals attached with a brass quick-connect terminal may lose their conductivity over time due to dissimilar material.
Alarms with self-driven oscillators require proper loading of the sound port for effective operation. These alarms are typically low-cost and produce continuous, intermittent, or chime tones. If the sound port is obstructed or covered to reduce the sound, it may cause a shift in the frequency output, or, in extreme cases, the alarm may not operate or may fail to produce the desired sound.
Direct driven alarms are commonly recommended for medical instruments, since the sound oscillator works independently of the loading of the sound port, and is more reliable for driving a piezoelectric disc to produce the desired tone. Direct driven alarms may be designed to produce any desired tone. Also, with self-driven oscillators, loading of the sound port may result in reduced sound levels, but will not shift the frequency or affect the alarm’s ability to operate.
Loudness and Type of Sound
When specifying a sounding device, design engineers need to factor in the desired volume as well as the type of sound. A primary consideration is to make sure that the alarm can be heard above environment noise, but not be so loud as to drown out other alarms and annunciators.
Alarms can produce a variety of tones, including continuous, chirp, intermittent, chime, warble, or siren. Continuous tone alarms produce a steady sound. Therefore, when specifying a continuous tone alarm, make sure that the sound does not blend in with environmental noises and thus be ignored. The CE-CM530AS continuous tone, panel mounted alarm is medium in volume, operating from 5 to 30 VDC. Output sound is about 97 ±3 dB (A) at 24 in. (61 cm). A chirp tone delivers a very short continuous sound, while an intermittent tone can be set with different pulse durations and frequencies to conserve power and to not be as “aggressive” as the continuous tone. The intermittent tone can be modified to reflect the urgency of the alarm by changing the interruption rate from a slow rate to a fast rate. The CE-BM530ASS, for example, is a panel-mounted alarm that delivers a medium loud intermittent tone, 1 pulse per second, operating from 5 to 30 VDC. Output sound is about 97 ±3 dB (A) at 24 in. (61 cm).
A chime tone delivery is a more pleasant sound, with the volume decaying exponentially. Typical applications for chime tones include nurse monitoring stations. The CE-HM530ASS is a panel-mounted alarm with a medium loud chime tone, 1 pulse per second, operating from 5 to 30 VDC. Output sound is approximately 95 ±3 dB (A) at 24 in. (61 cm).
A warble tone is designed to be more attention-getting, creating a sound that alternates between two distinguished frequencies. The CE-WM530ASS is a panel-mounted alarm with a medium loud warble tone, alternating at 1 Hz operating from 5 to 30 VDC. Output sound is about 97 ±3 dB (A) at 24 in. (61 cm).
A siren tone creates a sweeping sound between a low and high frequency, producing very loud sounds that are commonly utilized for noisy environments. The CE-US515BSS is a panel-mounted alarm with an ultra loud siren tone, 6 sweeps per second, operating from 5 to 15 VDC. Output sound is about 108 ±3 dB (A) at 24 in. (61 cm).
In addition, there are dual function alarms that combine two different sounds in one unit, thus minimizing the cost of the alarm. For example, in a dual function unit, there might be intermittent and continuous tones, chime and continuous tones, and warble and continuous tones. Another hard-to-find feature is a volume control to attenuate the sound level in special environments. The CE-EV offers a unique volume control rotor that can be mounted by the manufacturer or customer to attenuate the sound output level up to 20 dB from its loudest output.
ONLINE
For additional information on the technologies and products discussed in this article, visit Challenge Electronics at www.challengeelectronics.com.
Ely Zofanis the director of engineering for Challenge Electronics. He is responsible for all aspects of design and quality of piezoelectric alarms and transducers as well as assisting customers with their sound device needs. Zofan can be reached at 800-722-8197, x1009 or ezofan@challelec.com.
Challenge Electronics, Inc., Audible Products, 95 E. Jefryn Blvd., Deer Park, NY 11729
Posted on Monday, June 6th, 2011
An Introduction to Industrial Ethernet Connection Systems
By Michael Balekdjian, Application Engineer, METZ CONNECT (RIA CONNECT)
Unlike traditional office settings, Ethernet has spread into environments where protection from noise, solids, liquids and even gases is of concern. Manufacturing equipment and automated test environments are just some of the more common areas where standard RJ45 based connectors do not offer protection from these sources of contamination. Conditions in these environments warrant the use of industrial grade connectors and connection systems. The primary evolution involves encasing or shrouding the standard RJ45 in either a plastic or metal housing, depending on the application and required durability.
It is common to measure a connection system’s resistance to the aforementioned contaminants by what is known as the IP (ingress protection) rating, as defined by the International Electro-technical Commission (IEC 60529). Typically, connectors which carry can IP-67 rating are capable of provided adequate protection in even the harshest environments. Without outlining the specifics between various grades, the use and meaning behind IP-67 grade connection systems is as follows. The first digit represents the resistance against solids. In this case “6”, which happens to be the highest classification, and means the connector is dust tight or impervious to solids. The second digit represents resistance to liquids. A rating of “7” means the connection system can be submersed in one meter of water for up to one hour before leaking, and also resist moderate pressure water spray. This level of ingress protection can be provided by many of today’s industrial grade plastic housings. However, there are applications in which a metal solution is desired, especially if resistance to fire and even explosions is of concern. These normally consist of die-cast Zinc or nickel plated alloy housings, which also inherently provide complete protection from EMI.
Oil and gas exploration is one such area where network connections are not only subjected to liquids and gas, but also ultraviolet light, extreme temperatures, mud and very severe handling. All of these influences can increase the likelihood of network failures. Only the highest grade industrial strength connection systems will offer the protection required to maintain a working and reliable network connection in such an environment. For example, in a top-drive control application, it is imperative that control and data signal transmission be maintained.
This heavy and powerful piece of equipment is responsible for supplying the rotational force, or torque to facilitate the drilling of a well. It is also able to traverse vertically and is hydraulically actuated. Speed control, elevation and line pressure are important parameters to monitor to ensure adequate safety on the drilling platform. In addition, keeping the rig from becoming inoperable is second only to safety. The only time a rig should be inoperable is during a scheduled shut-down, such as when repositioning for a new well. Start-up and shut-down may account for just a few percent of operating time, but it is during this time that many incidents can occur. One such incident involves the disconnection and subsequent reconnecting of data signal and control cables. Most electrical related issues can be attributed to poor electrical contact. As if the abusive handing from rig operators is not enough to consider during this time, the connectors may be left free and become encrusted with mud, or even rolled on by heavy equipment while left dangling on the ground below. Protective caps are offered with many connectors so as to protect unused or temporarily disconnected ports from contamination. A ¼ turn bayonet style locking feature is used to facilitate quick connections, while providing high tensile strength support, which keep plugs from being pulled out of their receptacles. There is another industrial grade connection type connector, which was not enhanced or modified to bring Ethernet connectivity into harsh settings, as was the case with the traditional RJ-45. This connector type is known as an M-12 connector, and it has already been quite a popular choice for connecting devices used in industrial automation and control applications.
From inception, the design concept of the M-12 was to address the need for data acquisition and control functions in harsh environments. The strengthening and sealing of the RJ45 connector may provide a connection system comparable to that of an M-12 in terms of its IP rating, but the M-12 is inherently more robust and more compact than most RJ45 based systems. The attractiveness of the RJ45 based system is the lower upfront integration cost of some of the plastic based solutions, as well as using open protocols such as TCP/IP. This begins to phase out, once you consider metal based options, and it is arguable which offers superior performance. The M-12 was not necessarily designed with high speed data transfer in mind. However, much like the evolution of RJ45 based industrial connectors addressed the need for mechanical robustness and ingress protection; M12 connectors have been evolving to accommodate high speed networks, and two pair connectors can support data rates up to 100Mbs. Designs are currently underway to enhance the transmission performance of the M12, but don’t expect to see them replacing the traditional RJ45 style (8P8C) connector in the office. Doing so would be analogous to burning premium fuel in an engine designed to burn regular. This is a needless expense, as there is no net performance gain.
As is the case with most decision making, some of it will come down to pride of ownership, and certain beliefs which are formed based on others advice or experiences. Cost is always going to play a factor, and some of the metalized connection systems are on the high-end of that spectrum. Therefore, their use is best justified in applications like the one cited earlier in this discussion. Tradeoffs have to be analyzed and connectors chosen which offer the attributes necessary to ensure repeatable operation over the network’s, or at least the connector’s lifespan.
For more information, see www.riaconnect.com
METZ CONNECT (RIA CONNECT)
200 Tornillo Way
Tinton Falls, NJ 07712
(732) 389-1300
TLC Electronics, Inc. is an authorized distributor or METZ CONNECT (RIACONNECT) products. See www.tlcelectronics.com for more information on the products and services available from TLC Electronics, Inc.
Posted on Monday, June 6th, 2011
If your application requires interconnect solutions for aerospace, automotive, computer, consumer, entertainment, industrial, medical, packaging equipment, process control systems, security devices, telecom, white goods or vending, odds are that JST's vast array of connector offerings will provide a solution for your specific requirement. JST is proud to be the name behind many of the interconnect solutions hidden deeply inside the equipment found in many applications.
TLC is proud to be one of JST's premier distributors supplying high quality interconnect solutions at competitive prices. TLC has a trained staff ready to recommend one of JST's solutions or direct you to another connector manufacturer that will provide the best solution for your application.
TLC Electronics' value added services include design assistance, samples and prototypes, quick-turn delivery, sourcing, inventory management, production documentation, sub-assembly, sub-contractor management and higher-level assembly. Our extensive inventory will allow you to confidently reduce your interconnect lead time, enabling you to get your product to market quickly.
As one of TLC's leading interconnect manufacturers, TLC has made many of the JST part numbers available for purchase on our on line ordering page. See TLC's web page for more details on the use of our shopping cart feature.
For miniature IDC wire-to-board applications, the XSR series insulation displacement connectors offer a mounting height of 1.45mm and depth of 3.0mm. These IDC connectors utilize 36AWG, 7-strand wire providing the toughness and flexibility for reliability and freedom in wiring along with the space saving features. Available in circuit sizes from 2 to 22 positions, this wire-to-board solution also provides a secure locking feature with an audible 'click" to ensure proper mating. JST offers many fine pitch interconnect solutions. See JST for more information.
Many engineering and purchasing professionals think of JST as the fine pitch interconnect leader. However, in addition to leading the industry in fine pitch connection systems, JST also offers high quality standard D-subs, memory card connectors, lugs and terminals, waterproof connectors, USB, mini USB and uUSB, DC power jacks and automotive rated connectors. For complete details on the advanced connection system solutions offered from JST Corporation, please contact one of the TLCsolutions providers today at 651-558-2560 or tlcsales@gmail.com.
This is just a sampling of TLC Electronics' solutions for JST interconnect. To learn more about wire-to-wire, wire-to-board, board-to-board, I/O, communication interconnects, power connectors, and terminal blocks, click here.
Posted on Monday, June 6th, 2011
A Fan, an Impeller, or a Blower.
How to Choose The Right One For Your Application?
Reprinted with permission from Shyuan Ya
In thermal management, fans, impellers and blowers are classified as objects that force air at a volumetric rate to cool certain devices like a microprocessor. There are numerous types of air movement products including axial, propeller and tubeaxial fans. Other air movement devices consist of impellers and blowers (centrifugal & crossflow). Fans, impellers and blowers could be distinguished by their size and shape but more importantly, the flow of air (measured in CFM) given the static air pressure. A fan can basically have a high output of CFM with a lower level of air pressure, whereas blowers and impellers move smaller amounts of air at a greater level of pressure.
Basic Description of Fans, Impellers, and Blowers
Fans: Tubeaxial fans could vary in many sizes from 20x20mm (0.79" inches) to 172x51mm (6.77 inches). Fans are relatively inexpensive and readily available due to the high volume usage in the automotive, computer and power supply markets. Due to the low cost associated with tubeaxial fans, using tubeaxial fans is an efficient approach to dissipate heat. Axial fans, with axial airflow pattern, provide high performance airflow with relatively good efficiency. Also known as "box fans", the optimal operating performance of axial fans is at low-pressure or low system impedance conditions. One characteristic of the axial fan is that acoustic noise can be reduced (or increased) by modifying the fan speed. Shyuan Ya provides both AC fansand DC fans to meet your specific requirements.
Impellers: Impellers have the best performance when it comes to noise. Typically, they are less powerful when it comes to airflow,
but impellers do provide various airflow alternatives including tangential air flow.
Impellers provide an extremely efficient cooling method providing greater pressurization in water as opposed to fans. If your application requires AC impellers, Shyuan Ya and TLC can provide a solution.
Blowers: Blowers are usually installed in high system impedance applications that require back pressure. Applications include network servers and telecommunication systems. One drawback with blowers is their high level of noise compared to fans. Benefits include more concentrated airflow (largely due to the characteristic of intaking air from one side and releasing the air at a 90 degree angle directly at the substrate requiring cooling). AC blowersand DC blowersalso provide the option for single or dual air intakes.
Fan Construction
Shyuan Yadesigns and markets both inductive ACand brushless DC fans. The major raw materials that are used in the production of these fans include the following: housing, impellers, rotor, bearing, PC board, lead wires, and terminal leads (AC only).
Housing:
- housing materials used in the construction of Shyuan Ya DC fans consists of a plastic UL94V-0 material with a P.B.T. +30% GF black with numerous dimension and mounting options allowing for easy installation and maintenance.
- most AC fan housings are made of an aluminum painted / plastic material. Special materials are available upon request.
Impeller:
- the DC fan blades are made of a plastic with UL 94V-O P.B.T. AC fan blades are made of thermoplastic material.
Rotor:
- the rotor operates in a counter-clockwise direction. Shyuan Ya fans have a locked rotor protection where the fans were tested for a continuous period locked at the rated voltage and no damage was made.
Bearing:
- bearings can be classified as sleeve, dual ball, and ball/sleeve combination. Shyuan Ya bearings have a life of 30,000 hours for sleeve bearings, 45,000 hours for ball/sleeve combination and 60,000 hours for dual ball bearings.
PC Board:
- a PC board can be built into the fan and acts as the central control that keeps the fan operating. Special functions such as alarms and speed sensors can be added to the PC board to detect abnormal operating conditions.
Lead Wire:
- both DC and AC fans can have lead wires to connect to a power source. The standard lengths are 7 or 12 inches. Customers may specify lead wires lengths for the application. TLC can cut wires to length and terminate connectors to meet your specific requirements.
Terminal Leads:
- terminal leads offer an alternative for those designers that do not want permanent wires to the fan allowing for ease of replacement should the fan fail. Shyuan Ya provides this alternative terminal option for their AC line. TLC Electronics can also add extensions allowing for fans to be removed from an application without removing the entire wiring harness.
To read the entire article and to learn more about selecting the proper cooling device for your application, measuring bearing life expectancy, noise levels, measuring airflow, please click on this link totechnical support.
Sample stock is available should you have a prototype application that will require engineering testing and approval. To discuss sample availability, select a part number from the Shyuan Ya web site and contact TLC Electronicsfor sample delivery information.
To learn more about the cooling solutions offered from TLC Electronics and Shyuan Ya, please contact one of the TLCsolutions providers today at 651-558-2560 or tlcsales@gmail.com.
This is just a sampling of TLC Electronics' solutions for cooling sensitive electronic and electrical systems. To learn more about TLC's products and services, click here.
Posted on Thursday, April 29th, 2010
Mr. Jon Crofford has accepted a position in the TLC Electronics’ sales department as an account manager responsible for sales and service of accounts and prospects in a portion of the Minneapolis/St. Paul area and in northeastern Minnesota and northwestern Wisconsin. In addition, Crofford is responsible for Madison and Milwaukee Wisconsin area accounts and prospects.
Crofford has a BA in Graphics Management from University of Wisconsin Stout and has been employed full time with TLC Electronics since November of 2005. He has accepted progressive responsibilities within TLC over the last four and one half years including Process Improvement Team management, engineering and documentation control, and most recently, TLC’s Quick Response Manufacturing (QRM) program manager. Crofford is a creative thinker, an excellent communicator and very excited to become a part of the sales team. He is looking forward to working closely with our customers and prospects to provide solutions to their electromechanical component and assembly requirements.
Crofford will start in his new capacity beginning June 1, 2010. Until that time, you may contact Steven Olson at s.olson@tlcelectronics.com or the TLC sales staff at tlcsales@gmail.com if you have questions, concerns or a requirement for TLC Electronics’ products or services. Please see our web site at www.tlcelectronics.com.
