Allergies & Piezo Sensors

As many of you, I have been suffering of allergies, something very common for this time of the year.  It came to my mind to search about how piezodevices have helped in the fight of allergies.

Let start understanding what exactly are allergies.  I found a good definition for allergy in WebMD Allergies Health Center. A basic definition is “Allergies are an abnormal response of the immune system.  People who have allergies have an immune system that reacts to a usually harmless substance in the environment”[5].  Some of the most common substances are pollen, mold, animal’s hair; these substances are called allergens.

Inside our bodies, allergens’ story is more interesting.  In the presence of an allergy, we experience a changed of reactivity of our immune system.  This scenario causes the rise of Immunoglobulin E (IgE) an allergen-specific serum[4] .  The IgE molecules act as points of contact between the allergen and mast cells that release histamine and other agents upon exposure.  This initiates the events recognized as allergic reactions.  The rapid detection of IgE is very important when dealing with patients with an allergy, after a clinical evaluation based on patient's history and other testing, can help a physician confirm a diagnosis of atopic allergy and assist in the treatment of the patient[1].

If you want to know more about allergies and its relation with IgE, click here.

Now that we know a little more about allergies and IgE is time to know how piezodevices related these two things.  One of the approaches to test IgE uses piezoelectric crystals in which the anti-IgE antibody immobilized a gold or silver-coated crystal that serves as the receptor layer[2].  Let me explain a more, the anti-human IgE is deposited on the surface of the10 M Hz AT-cut gold coated crystal resonator by self-assembled technique, and serves as a receptor layer. The highly ordered self-assembled monolayers (SAMs) ensure well-controlled surface structure and offer many advantages to the performance of the sensor [3].

The piezo sensor can quantitatively detect human serum IgE in the range of 5-300 IU/ml with high precision (CV < 8%). The results are better than those given by two commercially provided test kits (Total IgE FAST Test, Pharmacia-CAP). The correlation coefficients are 0.94 between FAST and piezo sensor, and 0.90 between CAP and piezo sensor, respectively.  The uses of modified silver crystals increase the sensitivity, which brought better agreement[4].

The coated crystal can be reused after regeneration with urea and glycine buffer.  The coated crystal can be reused five times without appreciable loss of activity. This characteristic of regeneration for reused helps in the reduction of cost.

As we can see, piezo sensors are use to determine the IgE levels.  In addition, the results of test realize with the sensor are better than commercial test kits (FAST, Pharmacia-CAP).  At the same time, this approach for testing offers an economic factor to the laboratory performing the test.

References

[1]Important issues for allergen-specific IgE testing. Retrieved 5/9/2010, 2010, from http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/TipsandArticlesonDeviceSafety/ucm109367.htm

[2]Papamichael, K. I., Kreuzer, M. P., & Guilbault, G. G. (2007). Viability of allergy (IgE) detection using an alternative aptamer receptor and electrochemical means. Sensors and Actuators B: Chemical, 121(1), 178-186.

[3]Su, X., Chew, F. T., & Li, S. F. (1999). Self-assembled monolayer-based piezoelectric crystal immunosensor for the quantification of total human immunoglobulin E. Analytical Biochemistry, 273(1), 66-72.

[4]Su, X., Chew, F. T., & Li, S. F. Y. (2000). Piezoelectric quartz crystal based label-free analysis for allergy disease. Biosensors and Bioelectronics, 15(11-12), 629-639.

[5]WebMD allergies health center - find allergy information and latest health news. Retrieved 5/10/2010, 2010, from http://www.webmd.com/allergies/default.htm

What is Piezo Surgery?

I found this video that helps to understand, from the point of view of a physician, the benefits of Piezosurgery in general.  Dr.  Brock Lynn explains in a basic way how he uses piezosurgery in dental treatments, and what he considers its benefits.

Dr. Lynn received his DDS at Baylor College of Dentistry in 1980. He also completed his specialty training in Periodontics at Baylor in 1989, and is Board Certified in the specialty of Periodontics. He presented and published his master thesis and earned a Master of Science Degree in 1990 from Baylor.

As an active member of the Dallas County Dental Society, Dr. Lynn has served on the Society's peer-review/patient relations committee. He also holds membership in the Texas Dental Association, The American Academy of Periodontology, is a Fellow in the Academy of General Dentistry, and a member of the American Academy of Restorative Dentistry.

Piezoelectric Surgery

Usually, surgeries in which bones are part of, manual techniques or motor-driven instruments are use.  Manual instruments offer good control when used to remove small amounts of bone but not when precise cut must be done to a bone. In the case of motor driven instruments, an intense heat generated in the cutting zone and is necessary a constant water irrigation to control it.  This heat may affect the healing ability of the tissue of the surrounding area.

The need of less hand pressure using piezosurgery improved the operability and control.  In this way, the user can have a better precision for the cutting action because of microvibration of cutting tip. Also, the higher precision guarantees the cut of the bone without affecting soft tissue and almost bloodless area.  Reducing the bleeding let the surgeon have more visibility in the working area.

Oncologic Nasal Surgery

Piezosurgery has developed a system to cut bones without generating a premature death of cells or tissues.  This characteristic allows to consider it as the new scalpel in nasal surgery.

The University of Genoa, in Italy, has performed a study with Piezosurgery for the excision of malignant nasal tumors through a paralateronasal approach.  The surgery was realized in 10 patients affected by nasal adenocarcinoma.  This maligna cancer is usually developed on glandular cells specially on those lining in the cavities and organs of the body.

The piezodevice used for the surgeries utilizes low-frequency ultrasonic waves (24.7–29.5 kHz); according to the density of the bone, the power can be modulated and programmed.  The microvibrations are created in a piezoelectric hand piece.

The results of the study indicate that is a safety technique.  The piezosurgery do not register undesirable effects when other soft tissues were accidentally in contact with the microvibrating tip, not even bleeding.  In addition, any of the participating patients experienced unpleasant effects after the surgery.

Periodontology and Oral Implantology

Another application for piezosurgery is on the removal of supra and subgingival calculus deposits and preparing the root of the teeth for an implant; as members of Department of Periodontics of M.S. Ramaiah Dental College and Hospital in Bangalore, India, mentioned.For more detail click here.

Procedure as osteotomy (bone cutting) and bone replacement or reconstruction required careful removal of little amounts of bone to exposed root surfaces to avoid damaging the tooth surface.  For more detail click here.  

Also, the device is used for periodontal pocket wash with simultaneous ultrasonic tip movement, scaling, and crown lengthening.  In addition, with a change of the tip to a thinner and modifying the power setting the piezodevice can be used to remove lacerated or contaminated tissue and for root surface scaling to ensure thorough removal of calculus.

Brain Tumor Delineation in Neurosurgery

The diagnostic of a brain tumor is a scary situation deal with.  Most of the fear is based on the mental or physical disability that can become as side effects of the removal surgery.  During neurosurgical subtraction of brain tumor surgeons’ skill and caution are of vital importance.

However, the image innovations have helped the neuronavigation as guide during surgery is limited in accuracy.  So, the help of a sensor capable of estimating the difference between tissues has a particular importance in neurosurgical brain tumor removal.  The application of piezoelectric materials to design tactile sensors has been studied and reported in diverse research works.   The sensor is composed by two piezoceramic plates attached to a common beam. A spherical plastic tip is placed to improve tissue contact.

In this application, the technology is a support for the surgeon in determine with tissue should be removed.  Thus, the probability of removing healthy tissue and cause side damage is reduced.

Piezoelectric devices have proven to be a great support in a large number of medical and biotechnology applications.  This time I just mention three different areas of surgery that are using piezodevices to offer a higher quality treatment.

Knowing the piezoelectric devices

Piezoelectric devices are use in a wide range of medical application. Nowadays, most of the medical ultrasound transducers have the dual capacity to generate and receive an electric charge. However, other areas as surgical devices, dermatology and cosmetology, drug delivery, and laser ophthalmology; also incorporate piezoelectric devices in their treatment, prevention, or diagnostic of patients.

In 1880, Jacques and Pierre Curie published their experiments related to piezoelectricity; but the first practical application was in World War I. The technology was used to create an ultrasonic submarine detector. Since then piezoelectric devices have been use in a large range of applications.

The piezoelectric devices are those that use the piezoelectric effect to generate an electric charge under a mechanic stress, or vice versa. There are natural and man made materials that exhibit directly this effect, the most notably are crystal and certain ceramic, bone included. The especial characteristic of not been influenced neither create electromagnetic interference make piezodevices ideal for medical and biotechnology applications, as mention in Piezo motors & actuators.

Silently, the piezoelectric devices have been putting in our lives. Its progressive improvement has become a worldwide engine for innovation, enabling the development of new elements for the increasingly sophisticated applications. The realization in 1946 of the characteristics that the mixed ferroelectric barium titanate compound oxide (BaTiO3) could be converted to an electrical piezoelectric by poling process allowed the surprising admission of the piezo technology to the market, as presented in Chapter 1 of Piezoelectricity.

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As mention before piezodevices have advantages when use in medical equipment. However, among of them some have more attributes than others do, that are the case of ultrasonic linear piezomotors (also called resonant motors) and piezo stepper motors. Both are different in design, specifications, and performance according to Jim McMahon.

Ultrasonic piezomotors use a piezoelectric ceramic material to produce high-frequency acoustic vibrations and these create linear or rotary motion. They are use for large travel ranges, particularly when high speed is a requirement. Ultrasonic drives are considerably smaller than conventional electromagnetic motors. For detailed description of its operation click here

On the other hand, piezo stepper motors are form by numerous individual piezoactuators and generate motion through a succession of coordinated clamp/unclamp and expand/contract cycles. The motor could reach continuous motion when the actuators run at a high frequency. Physik Instrumente had developed the PiezoWalk, a piezo stepper motor, that can achieve much higher forces of up to 700 N compared with ultrasonic piezomotors.

After a general view of piezo devices, we are ready to know how this technology change and improve the medical treatments and diagnostics.