Authors: Dr. Avitus John Raakesh Prasad

Abstract

The TIXEL is a novel device based on a thermo-mechanical ablation technology, and combined sophisticated motion and temperature controls. The fractional technology is used to transfer very precise thermal energy to the dermis resulting collagen remodelling and it can create an array of microchannels or open channels which can be used in various applications involving the skin permeability of hydrophilic substances. This article helps in understanding this novel technology and its uses in dermatosurgery and aesthetic medicine.

Device: TIXEL from Novoxel, Israel. Indications: This technology can be used for several indications such as acne scars, wrinkles, skin rejuvenation, transepidermal permeation of various substances like Kojic acid, Tranexamic acid, Hyaluronic acid, Verapamil, Dicofenac, Magnesium ascorbyl phosphate. Facility: TIXEL can be carried out in a clinic or hospital setting or a nursing home with a small operation theatre. Informed consent and counselling: The dermatologic consultation should include detailed assessment of the patient's skin condition and skin type. An informed consent is mandatory to protect the rights of the patient as well as the practitioner.

All patients must have carefully taken preoperative and postoperative pictures. Parameters: Depends on the indication, type of scar, the site of the lesion, and the depth to be reached. Anaesthesia: There is acceptable pain and is tolerated well by patients but some may require topical anaesthesia. Postoperative care: Postoperative care is minimal. Post-treatment pain is minimal and redness settle in a few hour.
Keywords:Transdermal drug delivery, open channels, fractional skin ablation, acne scars, skin rejuvenation.

Introduction:

TIXEL uses a newer concept called Thermo-Mechanical Ablation (TMAb) technology. It includes an array of tiny titanium pins (1.25 mm pyramid-shaped, 3×10^-4 cm² surface area at the apex) called ‘the tip’ which is attached to a handpiece, equipped with a linear motor. By activating the handpiece, the linear motor rapidly advances the preheated tip to the skin surface at a predetermined ‘protrusion’ for a brief duration, thus creating micro-craters by vaporization of the stratum corneum and transfer of the heat to dermis.¹

For effective skin ablation and remodelling, temperature close to 400°C should be reached. A Co₂ laser ablation reaches that temperature. Tixel uses a sophisticated heating system which raises the temperature of the titanium tips to reach that particular temperature which is then imprinted on the skin delivering the heat to the skin. The tip auto sterilises as it reaches 400°C, and it sterilises between each contact with the skin. This feature is unique to TIXEL, which is not seen in other contact technologies like Microneedle RF, Sublative RF and Dermaroller microneedling.

In contrast to lasers, in which it causes an explosion and creates fumes or smoke, TIXEL does not cause blasting of epidermis while transferring the heat which is smoke free and less collateral damage to the surrounding epidermis.

The Equipment:

The Tixel has a

1. Base unit which houses the main mechanics and the screen for parameters ( Figure 1)
2. A sophisticated unique handpiece (Figure 2, 3)
Tixel’s Operation: the handpiece weighs ~270 grams. When the user places the handpiece flat on the skin and activates it, the linear motor rapidly advances the tip which comes in brief contact with the tissue. There is an opening in the distance gauge through which the tip can protrude at a desired length, usually 400 m beyond the distance gauge (Figure 2). The motion is perpendicular to the skin.











During tip motion the supply of electrical energy to the heater continues and all control operations are active. Controls operations include very precise monitoring of speed, protrusion distance and temperature of the tip. Thermal energy is transferred to the skin, creating micropores (or micro-craters) by evaporation. The tip recedes within a precisely controlled distance and time to its home position, away from the tissue. The duration of the pulse, i.e. time of contact between tip and skin, can be adjusted between 6ms to18ms.

A double pulsing mode is also enabled. The motor’s displacement accuracy is in the range of 1-8μm. A 14ms pulse delivers a high energy pulse of ~25mJ/pore while a 10ms pulse delivers a medium energy pulse of ~15mJ/pore and a 6ms pulse delivers a low energy pulse of ~10mJ/pore. The utilization of the Tixel does not require any protective eyewear or a smoke evacuator.

3. A titanium multiarray pyramidal tip.( Figure 4) It is made of Titanium over a gold plated copper tip. The tip is fixated at the distal section of the Tixel’s handpiece which is equipped with a linear motor. The tip's active surface consists of an array of 81 (9×9) pyramidal pins evenly spaced within a boundary area of 1×1cm.



The pin’s height is 1.25 mm having a radius of about 100 microns at the apex, meaning that each miniature pyramid contacts the skin over 3×10^-4 cm² surface area. The back plane of the tip is flat and is connected to a coin-size ceramic heater keeping the tip at a constant temperature of 400ºC during operation. The heater is pressurized against the tip by a spring to ensure good thermal matching of tip and heater. When not in use, the tip is base-positioned at a distance of 2 cm from the skin’s surface. The tip is re-usable. The system checks, validates, cleans, sterilizes tips automatically.



Tip’s Sterility: the system is designed to sterilize the tip before the system is ready for operation. When the tip reaches the temperature of 350°C, the system’s operation is blocked until the tip is heated to temperatures varying from 350°C to 400°C for duration of 3 minutes. Tip sterility has been evaluated in accordance with the requirements of ISO 20857 (ISO 20857 Sterilization of health care products -- Dry heat -- Requirements for the development, validation and routine control of a sterilization process for medical devices).

Sterility, which means an absence of all viable microorganisms including viruses, has been measured as a probability of no more than one viable microorganism per one million sterilized items of the final product (the generally accepted pharmacopoeial sterilization procedures is called ‘sterility assurance level’ (or SAL) of 1×10-6).



The theoretical and engineering foundations of the Tixel technology are described in reference.²

1. The temperature of the tip reaches 400°C, auto sterilises and the system is ready for operation Fig 5

2. Exposure time :
The exposure time ranges from 6 to 18 ms, this determines the time in which the tip is in contact with the skin.



Lesser contact time is needed when using for the non ablative mode, superficial ablation for skin rejuvenation and when treating superficial scars and wrinkles. When using contact time of 12ms and above the ablative mode is used for transfer of heat deeper for acne scars and pronounced wrinkles.

3. Protrusion :

Protrusion is the distance the tip travels into the skin for different levels of delivery of the heat and for more contact of the surfaces of the pyramidal tip for wider and deeper ablation. It goes from 200 to 700μm Protrusion of 200μm is used along with lesser exposure time when using for open channel mode which increases the skin permeability of hydrophilic substances like Hyaluronic acid, Verapamil,³ Dicofenac, Magnesium ascorbyl phosphate.

200μm with longer exposure time 8-10 ms is used in Periorbital pigmentation, and when treating bony areas. Protrusion of 400μm and above with longer exposure time 10-16 ms is used in skin rejuvenation, acne scars and wrinkles.



4. Pulse type:

There is a single and double pulsing in which the tip comes in contact with the skin with above parameters, either it touches the skin once or twice. This is to create lesser and more heat transfer in certain areas depending on the condition being treated. In Open channel its used in single pulse mode.

Mechanism of action:

Co² Fractional laser causes an explosion on the epidermis as it creates thermal injury to the dermis, this results in coagulation of the dermal tissue with epidermal charring and vapourisation.(Figure 6) In TIXEL it does not create an explosion but vaporises the epidermis without producing fumes or smoke, less collateral damage with thermal injury to the dermis. This explosion of a Co₂ fractional laser cause dendritectomy of the Melanocytes causing prolonged hypopigmentation seen in patients of FP skin type 4 to 6. This is not seen in TIXEL.

Tixel has ablative and non ablative modes, in Non ablative mode there is disruption of epidermis without charring and no injury to dermis( Figure 7), in Ablative mode there is disruption of epidermis and thermal injury to the collagen. (Figure 8). Biopsy photos Courtesy of NOVOXEL ISRAEL.



Case Discussion:

Case 1:
Tixel and Co₂ Fractional one session split face comparison, TIXEL parameters: Exposure Time – 12ms, Protrusion –600 μm, Pulse –Double. Co₂ Fraxel parameters : Energy per point – 45 - 60 mj, Dot space – 0.9 to 1.0 mm, Overlap –Double.

One treatment was done. Both side showed similar scar remodelling after 4 weeks. The Co₂ Fractional side showing persistent hypopigmentation as compared to the TIXEL side

Case 2:

A 32 year old female patient with post acne scars treated by TIXEL once in 4 weeks after 4 treatments showed excellent response. TIXEL parameters: Exposure Time – 12ms, Protrusion – 500 μm, Pulse –Double, whole area treated twice.



Case 3:

A 22 year old female patient with post acne scars treated by TIXEL once in 4 weeks after 4 treatments showed showing good improvement in scar depression and skin tightening. TIXEL parameters: Exposure Time – 12ms, Protrusion – 600 μm, Pulse –Double, whole area treated twice.

Case 4:

A 24 year old male patient with post acne scars treated by Subcision, TIXEL and Platelet Rich Plasma, once in 6 weeks after 2 treatments showed showing good scar reduction. TIXEL parameters: Exposure Time – 12ms, Protrusion – 600 μm, Pulse –Double, whole area treated twice. Combining various methods resulted in a faster and better improvement with fewer treatments in this patient. Figure 16

Advantages :

1. Novel non laser technology allows for a precise, accurate and painless tissue evaporation without causing undesired thermal damage to surrounding healthy tissue
2. Treatments are safe with fast healing times
3. Periorbital areas can be treated safely without the need for eye protection as in case of lasers.
4. Compact, light weight and portable device
5. No consumables costs as the tip is auto sterilised by heating
6. Cost effective
7. Safe and efficacious in acne scar treatment in IV to VI
8. Easy to use & delegatable
9. No Radiation as compared to other technologies.
10. Open channel technique will revolutionise the delivery of drugs and meso solutions.

Complications:

1. Mild pain and irritation during procedure and few hours post operative.
2. Use of less protrusion and lower contact time when treating over bony areas like the fore head and supraorbital and infraorbital margin.to prevent burns.
3. Infections can occur if the post op care is not followed.

Anaesthesia:

Anaesthesia is not required when using the open channel settings, but when treating scars use of topical anaesthetic is needed to reduce discomfort. The pain felt on during TIXEL is much less when compared to a Co2 fractional laser.

Contraindications:

1. This technology neither uses laser nor radiofrequency, it uses pure heat which is safer in most patients unless the skin is compromised by chronic skin conditions, ultraviolet light related skin conditions, sensitive skin syndrome.
2. Pregnancy as for any procedure.
3. Pre-existing skin infections which should be treated accordingly before attempting TIXEL.

Conclusion:

The clinical effects of TIXEL in its ablative mode and CO2 lasers is are similar owing to the identical thermal energy delivered to the tissues within similar time duration and similar depth. However, TIXEL ablative mode has two special advantages:
1. It is easier to use, i.e., there is no smoke, protective eyewear is not required, and there is no risk of accidental application of invisible laser radiation for the patient, physician or personnel.
2. Faster recovery and less downtime. In addition, by applying shorter exposure time, tissue effects that are closer to erbium laser effects are achievable.

The Non-ablative TIXEL mode whereby skin crushing is achieved, we see two major advantages unattainable with lasers.
1. Using this mode, it is possible to cause thermal heating of the epidermis down to the papillary dermis, without vaporizing the stratum corneum. As a result, a natural physiologic dressing against infection may be present. The stratum corneum in this mode is not expelled by cellular explosion as with lasers, due to the sealing effect of the tip when less energy is applied. However, beneath the epidermis, the temperature increases to the tip temperature of 400 °C leading to vaporization and damage to cells.
2. Micro-channels or Open channels which is unique to TIXEL are formed between the cells (as seen in Figure 7).This ability of TIXEL allows higher permeability of hydrophilic drugs which normally don’t penetrate the skin. Various studies are being conducted to show the efficacy of TIXEL as a newer method in transdermal drug delivery.⁴

In conclusion, TIXEL technology is as efficient as CO2 lasers while being less painful, safer, as well as more compact and much simpler to user. It provides a high versatility and in many senses is more than a combination of CO2 and erbium laser.

References:

1. Elman M, Fournier N, Barnéon G. Fractional treatment of aging skin with Tixel, a clinical and histological evaluation. J Cosmet Laser Ther. 2016;18(1):31-7.
2. Lask G, Elman M, Fournier N, Slatkine M, "Fractional vaporization of tissue with an oscillatory array of high temperature rods – Part I: Ex vivo study". J Cosmet Laser ther. 2012; 5:218-223,
3. Sintov AC, Hofmann MA. A novel thermo-mechanical system enhanced transdermal delivery of hydrophilic active agents by fractional ablation. Int J Pharm. 2016 Sep 25;511(2):821-30.
4. Lee JW, Gadiraju P, Park JH, Allen MG, Praunitz MR. Microsecond Thermal Ablation of Skin for Transdermal drug Delivery. J Control Release. 2011, 54(1):58-68